Laser Processing Method for Silicon Substrate Cutting
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Solution Overview
Problem
Conventional laser processing methods using 1300 nm wavelength laser light for cutting silicon substrates result in a higher transmittance and easy fracture formation, leading to reduced accuracy and increased meandering of fractures, which lowers the cutting accuracy and increases the number of modified regions needed.
Innovation Solution
A laser processing method that modulates laser light using a spatial light modulator with a quality pattern to form modified regions at specific positions, including an intermediate position between the main faces of the object, to reduce the number of rows of modified regions and prevent continuous fracture advancement in the thickness direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-power laser processing is used to increase productivity, then processing speed improves, but heat-affected zone expands causing deformation and cracks
Solution Approach 1:
The patent applies periodic pulsed laser irradiation instead of continuous high-power laser processing. By controlling the laser to operate in pulse mode with specific duty cycles, the method enables high productivity during the laser on-periods while allowing heat dissipation during off-periods, thus preventing excessive heat accumulation that causes deformation and cracks in the heat-affected zone.
Solution Approach 2:
The patent introduces a protective atmosphere (inert gas or vacuum) before laser processing to cushion against harmful effects. This pre-established protective environment prevents oxidation and reduces thermal stress during high-power laser processing, thereby maintaining manufacturing precision while achieving high productivity through faster processing speeds.
2Productivity
If high-power laser processing is used to increase productivity, then processing speed improves, but cracks occur in processed material
Solution Approach 1:
The patent uses periodic pulsed laser irradiation to achieve high processing speeds while preventing cracks. The pulsed operation allows controlled heat input during laser on-periods and heat dissipation during off-periods, preventing thermal stress accumulation that leads to cracking, thus maintaining material reliability even at high productivity levels.
Solution Approach 2:
The patent employs an inert atmosphere (such as nitrogen or argon gas, or vacuum environment) during laser processing to create a protective environment. This inert environment prevents oxidation and reduces thermal stress on the processed material, thereby preventing crack formation and ensuring reliability while maintaining high processing speeds for improved productivity.
3Device complexity
If conventional laser processing methods are used, then equipment complexity remains low, but dross attaches to processed surface requiring additional steps
Solution Approach 1:
The patent introduces oxygen or oxygen-containing gas during laser processing to accelerate oxidation of molten metal, causing dross to form and float to the surface. This controlled oxidation process enables easy removal of dross from the processed surface, improving surface quality and manufacturing precision while maintaining relatively simple processing equipment without requiring complex additional removal systems.
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 reduces the number of modified regions in the thickness direction while maintaining cutting accuracy, preventing fractures from extending in the thickness direction and ensuring precise cutting along the intended line.
Implementation Method 1
a laser beam is made to irradiate a metal plate material in a laser beam irradiation direction L1 extending in a plate thickness direction of the metal plate material
Implementation Method 2
molten metal is solidified in a specific direction
Data Source
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AI summary
For modulating laser light for forming a modified region SD3 at an intermediate position between a position closer to a rear face 21 and a position closer to a front face 3 with respect to an object 1, a quality pattern J having a first brightness region extending in a direction substantially orthogonal to a line 5 and second brightness regions located on both sides of the first brightness region in the extending direction of the line 5 is used. After forming modified regions SD1, SD2 at positions closer to the rear face 21 but before forming modified regions SD4, SD5 at positions closer to the rear face 21 while using the front face 3 as a laser light entrance surface, the modified region SD3 is formed at the intermediate position by irradiation with laser light modulated according to a modulation pattern including the quality pattern J.