Semiconductor Wafer Laser Slicing With Overlapping Modified Points

The laser scanning process is divided into multiple passes (first laser scan and second laser scan), where each pass creates modified points at different positions. The first scan creates initial modified points, and the second scan creates additional modified points with overlap, segmenting the modification process to achieve better precision without requiring excessive energy in a single pass.

The laser scanning is performed periodically with multiple scans across the same region. The laser beam repeatedly scans the crystal ingot surface, creating modified points in a periodic manner. This periodic action allows the modified points to accumulate and overlap, enhancing the separation effect while maintaining controlled processing time through systematic repetition.

The patent combines two different laser scanning processes into one unified method. The first laser scan and second laser scan are merged into a single processing workflow, where both scans work together to create the desired modified points. This merging approach achieves the precision benefits of using different pulse widths while maintaining a relatively simple device architecture by using the same laser system for both scans.

The laser scanning parameters are changed between the first and second scans. The scanning speed, pulse repetition frequency, or other laser parameters are adjusted to create different modified point characteristics in each scan. This parameter variation allows precise control over the modified points without requiring fundamentally different laser systems, thereby reducing device complexity.

The laser scanning process maintains continuous useful action by performing multiple overlapping scans. Instead of relying on a single high-speed pass that might compromise precision, the system performs multiple scans that collectively cover the entire separation surface. The continuity of this multi-scan process ensures that no region is missed, maintaining precision while allowing optimized scanning speeds.

The patent applies partial action by performing multiple scans that overlap beyond what a single scan would provide. The modified points from the first scan and the modified points from the second scan overlap in certain regions, creating an excessive action effect in those areas. This ensures thorough modification and burr reduction at the separation surface, maintaining precision even at higher scanning speeds.