Laser Slit Alignment for Consistent Wafer Dividing Groove Depth
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Solution Overview
Problem
The center line of the laser beam may be displaced in the width direction of the slit due to secular degradation in a laser oscillator, causing the dividing grooves to not have a predetermined depth.
Innovation Solution
A laser processing apparatus is designed with a slit moving mechanism and an adjusting unit to ensure that the center of the slit and the cross-sectional center of the laser beam coincide, using a power meter and a camera to adjust the position of the slit for maximum power and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a slit with narrow width is used to form dividing grooves, then the width of dividing grooves is narrowed to produce more chips, but the center line of the laser beam may be displaced from the center of the slit due to secular degradation, causing insufficient power to form grooves of predetermined depth
Solution Approach 1:
The adjusting unit performs preliminary alignment of the slit center with the laser beam cross-sectional center before the actual groove formation process. This preliminary action ensures that the laser beam is properly centered on the slit, preventing power insufficiency and ensuring grooves of predetermined depth are formed from the start.
Solution Approach 2:
The adjusting unit uses feedback from power meter measurements or camera imaging to detect the relative position between the slit center and laser beam center. Based on this feedback, the system automatically adjusts the slit position to achieve optimal alignment, ensuring sufficient laser power reaches the wafer to form grooves of the required depth.
2Device complexity
If the slit position is fixed without adjustment, then the device complexity is reduced, but the center of the slit and cross-sectional center of the laser beam cannot be ensured to coincide, leading to processing defects
Solution Approach 1:
The patent replaces complex mechanical alignment mechanisms with an automated adjusting unit that uses power meter measurements or camera imaging to automatically align the slit with the laser beam. This substitution maintains high reliability through automated feedback control while avoiding the complexity of manual mechanical adjustment systems.
Solution Approach 2:
The adjusting unit enables the system to self-align by automatically detecting the misalignment between the slit center and laser beam center through power measurements or camera imaging, and then autonomously adjusting the slit position to achieve optimal alignment without requiring external manual intervention.
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 solution ensures that the laser beam power is sufficient to form dividing grooves of a predetermined depth, preventing insufficiency and processing defects, and allowing for the formation of appropriate-shaped grooves in wafers.
Implementation Method 1
a power meter configured to measure power of the laser beam passed through the slit
Implementation Method 2
a camera disposed on a back side of the mirror, and configured to image a transmitted laser beam as the laser beam emitted from the laser oscillator and passed through the mirror
Implementation Method 3
a mirror configured to reflect the laser beam emitted from the laser oscillator and irradiate the wafer held on the chuck table with the laser beam
Implementation Method 4
a laser processing apparatus performs ablation processing that forms dividing grooves extending in an X-axis direction in the surface of a wafer by irradiating the wafer with a laser beam
Data Source
AI summary
A laser processing apparatus includes a laser oscillator configured to emit a laser beam, a slit configured to narrow a width of the laser beam emitted from the laser oscillator to a width corresponding to a dividing groove to form the dividing groove of a predetermined width, a slit moving mechanism configured to move the slit in a direction corresponding to a width direction of the dividing groove, and an adjusting unit configured to make the center of the slit and the cross-sectional center of the laser beam entering the slit coincide with each other in a direction in which the slit moving mechanism moves the slit.