Laser Separation Start Point Formation for SiC Facet Regions
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Solution Overview
Problem
In silicon carbide (SiC) single crystal wafers, the facet region exhibits a higher energy absorption rate than the non-facet region, leading to insufficient laser-induced separation layers and potential separation failures due to weaker laser beam intensity, which is not effectively addressed by existing methods.
Innovation Solution
A method involving laser processing with specific region setting and controlled feed movements forms a separation start point by creating modified portions within the workpiece, adjusting the interval between these portions to ensure uniformity and strength across different regions, thereby enhancing the separation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser beam processing is performed on the facet region, then separation layer formation is attempted, but the separation layer is insufficient due to higher energy absorption rate and weaker laser beam intensity
Solution Approach 1:
The patent applies different processing strategies to different regions of the workpiece. Specifically, the facet region and non-facet region are treated differently through region-specific laser processing parameters and multiple processing passes, ensuring each region receives appropriate energy density for uniform separation layer formation despite their different absorption characteristics
Solution Approach 2:
The patent performs preliminary laser processing to form a separation start point before completing the full separation. This preliminary action creates an initial modification in the facet region that facilitates subsequent separation, addressing the energy absorption issue by preparing the material structure in advance
2Manufacturing precision
If laser beam intensity is increased to compensate for higher energy absorption in facet region, then separation layer formation improves, but risk of damage and overheating increases
Solution Approach 1:
The patent employs periodic laser processing with multiple passes and intervals. The laser beam processes the workpiece in repeated cycles, allowing heat dissipation between passes and preventing overheating while still achieving sufficient separation layer formation through cumulative energy input
Solution Approach 2:
The patent applies laser energy selectively and partially to different regions. Rather than uniformly high intensity across the entire facet region, the processing is applied in controlled portions with varying parameters, achieving adequate separation layer formation without excessive energy input that would cause damage
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
The method effectively suppresses separation failures by ensuring consistent laser-induced separation layers, particularly in the facet region, thereby improving the reliability of the separation process.
Implementation Method 1
a condensing point of a laser beam is relatively moved in a processing feed direction with respect to the workpiece while a laser beam is emitted toward the first surface with the condensing point positioned inside the workpiece to form a strip-shaped modified portion inside the workpiece
Implementation Method 2
The facet region has a higher energy absorption rate than the non-facet region. Therefore, in the facet region, the intensity of the laser beam reaching a condensing point is weaker
Data Source
AI summary
A method is of forming, inside a workpiece having first and second surfaces, a separation start point for separating the workpiece into the first and second surface sides. The method includes: holding the workpiece to expose the first surface; setting a specific region on the first surface; and repeating processing feed and indexing feed to form modified portions inside the workpiece and form a separation start point including the modified portions. The processing feed is of relatively moving a condensing point of a laser beam in a processing feed direction with respect to the workpiece while emitting the laser beam toward the first surface with the condensing point positioned inside the workpiece to form a strip-shaped modified portion inside the workpiece. The indexing feed is being of relatively moving the condensing point in an indexing feed direction, orthogonal to the processing feed direction, with respect to the workpiece.