Laser Processing Apparatus Yawing Correction via Pattern Mapping
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Solution Overview
Problem
The existing laser processing apparatuses face issues with yawing in the Y direction, which can cause the laser beam to deviate from the division lines, potentially damaging the devices during the ablation process.
Innovation Solution
A laser processing apparatus equipped with a controller that includes a target pattern detecting section, spacing detecting section, map creating section, pass/fail determining section, and position correcting section to detect and correct yawing by creating a map of the spacing between target patterns and ablation grooves, determining accuracy, and adjusting the laser beam position accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the feeding means is used to relatively feed the chuck table and laser beam applying means in the X direction, then the ablation groove can be formed along the division line, but yawing in the Y direction causes the laser beam to deviate from the division line
Solution Approach 1:
The imaging unit captures images of the wafer surface, and the controller processes these images to detect the actual positions of division lines and ablation grooves. The system uses this feedback information to calculate yawing amounts and determine whether they exceed predetermined thresholds, enabling real-time monitoring and correction of alignment deviations caused by feeding means yawing.
Solution Approach 2:
The patent replaces purely mechanical alignment methods with an optical measurement system. Instead of relying solely on the mechanical precision of the feeding means, the system uses an imaging unit to optically detect the actual positions of division lines and ablation grooves, substituting mechanical trust with optical verification and computational analysis.
2Productivity
If the laser beam is applied along each division line to form an ablation groove, then the wafer can be divided into individual devices, but the ablation groove must not deviate from the division line width to avoid damaging devices
Solution Approach 1:
The imaging unit continuously monitors the position of the ablation groove relative to the division line during the laser processing. The controller calculates the spacing between the ablation groove and division line center, and when this spacing exceeds a predetermined threshold indicating potential device damage, the system can alert operators or adjust parameters to prevent harmful effects.
Solution Approach 2:
The system performs preliminary imaging and position detection before completing the ablation process. By detecting the actual positions of division lines and calculating expected ablation groove positions in advance, the system can predict potential deviations and take preventive measures before device damage occurs, rather than reacting after damage has happened.
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 allows for accurate detection and correction of yawing, preventing laser beam deviation from division lines and minimizing damage to devices, enabling precise ablation groove formation even when yawing occurs.
Implementation Method 1
an imaging unit for imaging a work area
Implementation Method 2
laser beam applying means having focusing means for applying the laser beam to the wafer held on the chuck table
Implementation Method 3
applying a laser beam to a wafer along a plurality of crossing division lines to form an ablation groove along each division line by ablation
Data Source
AI summary
Disclosed herein is a laser processing apparatus including a controller. The controller includes a target pattern detecting section performing matching between patterns formed in each device imaged and a key pattern to thereby detect a target pattern included in each device, a spacing detecting section detecting the spacing in a Y direction between the target pattern and an ablation groove formed along each division line by ablation, and a map creating section creating a map showing the spacing in the Y direction between each target pattern and the ablation groove for the plural devices arranged along the ablation groove.