Laser Processing System Astigmatism Positioning Control
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Solution Overview
Problem
Conventional laser processing apparatuses face challenges in accurately forming a modified region that serves as a cutting start point at a desirable position within the object to be processed, which affects cutting quality.
Innovation Solution
The laser processing apparatus positions the converging point of the second laser light between the focal point and the converging lens, allowing for a larger acquirable area of positional information and reducing adverse effects from cutting marks, while emitting both laser lights simultaneously to ensure precise formation of the modified region at a predetermined distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the converging point of the second laser light is positioned at the focal point of the converging lens, then the measurement precision is maximized, but the acquirable area of positional information is limited and adverse effects from cutting marks increase
Solution Approach 1:
The patent changes the position parameter of the second laser light's converging point from the focal point to a position between the focal point and the converging lens. This parameter change expands the acquirable area of positional information while maintaining sufficient measurement precision, resolving the contradiction between measurement accuracy and measurement range.
2Measurement precision
If the converging point of the second laser light is positioned at the focal point of the converging lens, then the measurement precision is maximized, but light scattering from cutting marks increases
Solution Approach 1:
By changing the position parameter of the second laser light's converging point to be between the focal point and the converging lens, the patent reduces the density of cutting marks in the measurement area. This parameter adjustment minimizes light scattering from cutting marks while preserving adequate measurement precision.
3Manufacturing precision
If the focal point of the converging lens is positioned within the object, then the modified region can be formed at deeper positions, but the acquirable area of positional information shrinks
Solution Approach 1:
The patent adjusts the position parameter of the second laser light's converging point to be between the focal point and the converging lens. This creates an overlapping measurement range that allows positional information to be acquired even when the focal point is positioned within the object at deeper locations, thereby enabling modified region formation at depth while maintaining an adequate acquirable area.
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 enables accurate and precise formation of the modified region at a desirable position, enhancing cutting quality by expanding the acquirable area of positional information and minimizing light scattering from cutting marks.
Implementation Method 1
converging point position control means detects reflected light of the second laser light reflected by a laser-light-irradiated surface of an object to be processed and regulates the position of the converging point of the first laser light
Implementation Method 2
converging point position control means detects reflected light of the second laser light reflected by a laser-light-irradiated surface
Data Source
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AI summary
A laser processing apparatus comprises a converging lens 31 for converging processing laser light and rangefinding laser light L2 toward a wafer 1, an actuator for actuating the lens 31, a shaping optical system 49 for adding astigmatism to reflected light L3 of the rangefinding laser light, a quadrant photodiode 42 for receiving the reflected light L3 and outputting voltage values corresponding to its light quantities, and a controller for regulating the actuator, and positions a converging point P2 of the rangefinding laser light L2 between a focal point P0 of the lens and the lens 31, so as to make it possible to form a modified region at a position deeper from the front face 3, thereby suppressing adverse effects due to the reflected light L3. The control is based on an arithmetic value subjected to a division by a sum of the voltage values, so as to prevent the arithmetic value from being changed by the quantity of reflected light.