Semiconductor Wafer Laser Cleaving With Controlled Internal Cracks
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Solution Overview
Problem
The existing methods for cutting semiconductor wafers using laser beams often result in cracks reaching the surface of the substrate, which can lead to chipping of the substrate during the cutting process.
Innovation Solution
A method involving multiple laser irradiation steps to form specific modified portions within the substrate, where the laser beam is scanned along cutting streets to create a controlled crack extension, reducing the likelihood of substrate chipping by managing the strain release and crack propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cracks are formed that reach the surface of the substrate from each of the two rows of modified regions, then the substrate can be divided, but the substrate may be chipped when cut
Solution Approach 1:
The patent applies local quality by creating modified regions with different characteristics at different locations. Specifically, it forms a first modified region and a second modified region with different laser irradiation conditions, resulting in different crack propagation behaviors. The first modified region generates cracks that extend toward the first surface, while the second modified region generates cracks that extend toward the second surface, but with controlled differences in extension depth and direction, achieving localized control over crack behavior to prevent chipping while maintaining cuttability.
Solution Approach 2:
The patent applies preliminary action by pre-forming modified regions within the substrate before the actual cutting operation. These modified regions are created through laser irradiation that induces structural changes in the substrate material, preparing predetermined paths for crack propagation. This preliminary modification ensures that when cutting is performed, cracks will follow the desired paths without causing unwanted chipping, as the substrate has already been prepared with controlled weakness zones.
2Productivity
If multiple rows of modified regions are formed to facilitate cutting, then cutting efficiency is improved, but the number of cracks reaching the surface increases leading to more chipping
Solution Approach 1:
The patent applies local quality by creating modified regions with different characteristics at different locations. Specifically, it forms a first modified region and a second modified region with different laser irradiation conditions, resulting in different crack propagation behaviors. The first modified region generates cracks that extend toward the first surface, while the second modified region generates cracks that extend toward the second surface, but with controlled differences in extension depth and direction, achieving localized control over crack behavior to prevent chipping while maintaining cuttability.
Solution Approach 2:
The patent applies parameter changes by varying the laser irradiation parameters for different modified regions. It uses different laser输出功率 (output power), scanning speeds, or focusing conditions when creating the first modified region versus the second modified region. These parameter changes result in modified regions with different structural properties, controlling the depth and direction of crack extension from each region, thereby managing crack propagation to reduce chipping while maintaining cutting efficiency.
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 effectively minimizes substrate chipping during cutting by promoting controlled crack formation and extension, facilitating easy cleavage of thick substrates while reducing the number of cracks that contribute to substrate splitting from the surface side.
Implementation Method 1
irradiating a laser beam from a first surface of the substrate to an interior of the substrate along a first direction parallel to the first surface
Implementation Method 2
a modified portion that is more brittle than a portion having undergone no laser beam irradiation is formed in a laser beam irradiation section (focusing section)
Implementation Method 3
when strain generated at the time of forming a modified portion is released, a crack is formed that extends from the modified portion toward at least the first surface of the substrate
Implementation Method 4
a crack is formed that extends from the modified portion toward at least the first surface of the substrate
Data Source
Figure 1
Figure 2~3A
Figure 3B~4A
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.