Semiconductor Substrate Laser Cleaving with Depth-Controlled Crack Paths
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Solution Overview
Problem
The existing methods for cutting semiconductor wafers using laser beams often result in chipping of the substrate due to cracks formed on the surface, which can lead to substrate damage during the cutting process.
Innovation Solution
A method involving multiple laser irradiation steps to create specific modified portions within the substrate, where cracks are strategically formed and extended to facilitate clean cutting without surface chipping, involving first, second, and third irradiation steps to align and position modified portions for efficient crack propagation and substrate separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If two rows of modified regions are formed by laser beam irradiation along first and second straight lines, then the wafer can be divided by cracks extending from the modified regions, but the substrate may be chipped when cut
Solution Approach 1:
The cutting street is divided into multiple regions with different modified portions (first, second, and third modified portions) positioned at different depths and locations. This segmentation allows cracks to propagate through specific regions while avoiding surface chipping, as the modified portions are strategically placed to control crack paths without reaching the surface uniformly.
Solution Approach 2:
The invention introduces a depth dimension by forming modified portions at different positions in the thickness direction of the substrate. The first modified portions are formed at a first depth, second modified portions at a second depth, and third modified portions at a third depth closer to the surface. This three-dimensional arrangement controls crack propagation in the depth direction while preventing surface chipping.
2Ease of manufacture
If cracks extend from modified regions to the substrate surface, then the substrate can be divided, but chipping occurs during cutting
Solution Approach 1:
Different regions of the cutting street are given different properties through selective laser irradiation. The first modified portions are formed at positions that allow crack propagation, while the third modified portions are formed closer to the surface to control and limit crack extension. This local differentiation ensures cracks propagate through the substrate for division but do not cause surface chipping.
Solution Approach 2:
The laser beam forms modified portions in advance at specific positions and depths before cutting occurs. The first and second modified portions are formed at deeper positions to initiate crack propagation, while third modified portions are formed closer to the surface to control crack paths. This preliminary modification ensures controlled cracking without surface damage during the subsequent cutting process.
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 reduces the likelihood of substrate chipping during cutting by controlling crack formation and propagation, allowing for precise and effective separation of semiconductor elements without surface damage.
Implementation Method 1
a laser beam is irradiated from a first surface side to an interior of the substrate to form a plurality of first modified portions aligned along the first direction in the interior of the substrate
Data Source
AI summary
A method of manufacturing a semiconductor element includes a first irradiation step in which a laser beam is irradiated to form, in the interior of the substrate, a plurality of first modified portions aligned along a first direction; a second irradiation step in which a laser beam is irradiated to form a plurality of second modified portions aligned along the first direction at a position adjacent to the plurality of first modified portions in the second direction; and a third irradiation step which a laser beam is irradiated to form a plurality of third modified portions aligned along the first direction at a position closer to the first surface than the first modified portions and overlapping the plurality of first modified portions in a thickness direction of the substrate.