Laser Chip Cutting via Intermediate Modified Regions
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Solution Overview
Problem
Conventional laser processing methods fail to accurately cut objects due to variations in thickness and cleavage characteristics, leading to deviations and uneven cuts.
Innovation Solution
A laser processing method that forms first and second modified regions in a row in the thickness direction, with a third modified region positioned between them, to create a fracture that advances along the line to cut, preventing deviations and ensuring accurate cutting. This method uses multiphoton absorption to generate modified regions, such as crack or molten processed regions, within the object.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple modified regions are formed sequentially from the opposite side of the laser light entrance surface, then the cutting process can be completed, but the end part of the cut section deviates greatly from the line to cut due to fracture extension along cleavage planes
Solution Approach 1:
The patent applies preliminary action by forming the third modified region between the first and second modified regions before completing the formation of the second modified region. This intermediate modification creates a controlled fracture path that prevents uncontrolled fracture extension along cleavage planes, thereby maintaining cutting accuracy while ensuring reliable fracture control throughout the process.
2Manufacturing precision
If the fourth modified region is formed between the third modified region and the laser light entrance surface, then the cut section becomes more controlled, but the laser light scattering and absorption increases affecting the formation of the third modified region
Solution Approach 1:
The patent segments the modified regions into a specific sequence (first, third, second, then fourth) to optimize the balance between cut section uniformity and laser light efficiency. By forming the fourth modified region after the third modified region, the patent ensures that the critical third region is formed before laser light scattering and absorption from the fourth region can interfere, thus maintaining both cut section uniformity and laser light efficiency.
3Productivity
If modified regions are formed in conventional order, then the processing can be completed, but the number of modified regions required increases for objects with large thickness
Solution Approach 1:
The patent applies dimensionality change by forming the third modified region in an intermediate position between the first and second modified regions in the thickness direction. This strategic placement in the intermediate dimension allows a single third modified region to bridge and connect fractures across larger thicknesses, reducing the total number of modified regions required while maintaining processing efficiency for objects with large thickness.
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 method enables highly accurate cutting along a line to cut, even for objects with large thickness, by controlling fracture propagation and reducing the number of modified regions required, thus improving cut quality and efficiency.
Implementation Method 1
Each modified region is formed by generating multiphoton absorption or other kinds of absorption within the object upon irradiating the object with laser light while locating a converging point within the object
Data Source
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AI summary
An object to be processed can be cut highly accurately along a line to cut. An object to be processed 1 is irradiated with laser light while locating a converging point within a silicon wafer 11, and the converging point is relatively moved along a line to cut 5, so as to form modified regions M1, M2 positioned within the object 1 along the line to cut 5, and then a modified region M3 positioned between the modified regions M1, M2 within the object 1.