Laser Substrate Splitting With Outer-Edge Crack Preprocessing
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Solution Overview
Problem
The existing methods for manufacturing semiconductor substrates using wire saws result in significant material wastage and surface irregularities, leading to low productivity due to large cutting allowances and instability in laser-induced separation layers, which can cause chipping during substrate splitting.
Innovation Solution
A manufacturing method that forms a separation layer with modified parts and cracks inside the ingot using a laser beam, where the focal points are strategically positioned and moved relative to the ingot to create a stable separation layer, allowing for easier substrate splitting with reduced chipping by promoting crack extension in the outer circumferential region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a substrate is split off from the outer circumferential region of the ingot without preliminary processing, then the splitting-off process is simpler, but large chipping occurs in the outer circumferential region
Solution Approach 1:
The patent applies preliminary action by forming modified parts in the outer circumferential region before the main separation layer formation. This preliminary modification creates a foundation that prevents chipping during subsequent splitting operations, resolving the contradiction between process simplicity and manufacturing precision.
2Reliability
If the laser beam power is increased to ensure sufficient modified parts and cracks in the outer circumferential region, then the separation layer formation is more reliable, but the risk of large chipping during splitting increases
Solution Approach 1:
The patent applies local quality by using different laser beam powers for different regions: a first power for the outer circumferential region and a second power (higher than the first) for the inner region. This regional differentiation ensures reliable separation layer formation while preventing excessive chipping in the outer region.
3Length of stationary object
If the focal point is positioned deeper in the ingot to form the separation layer, then the separation depth is sufficient, but the power of the laser beam focused in the internal of the ingot becomes unstable
Solution Approach 1:
The patent applies preliminary action by first forming modified parts at a shallower depth in the outer circumferential region before forming the separation layer at the target depth. This staged approach allows the laser beam to gradually reach the deeper separation layer position, maintaining power stability throughout the 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 method enhances the splitting-off process, reduces material wastage, and improves substrate productivity by stabilizing the laser beam power and promoting crack formation in the outer circumferential region, thereby minimizing chipping and increasing the efficiency of substrate production.
Implementation Method 1
forming a separation layer including modified parts and cracks that extend from the modified parts, inside the workpiece, by irradiating the workpiece with a laser beam
Implementation Method 2
moving focal points on which the laser beam is focused and the workpiece relative to each other in a state in which the focal points are positioned to the outer circumferential region
Implementation Method 3
irradiating the workpiece with a laser beam with such a wavelength as to be transmitted through a material that configures the workpiece
Data Source
AI summary
A preliminary processing step of forming modified parts in an outer circumferential region of a workpiece is executed prior to a main processing step of forming modified parts and cracks in each of plural linear regions included in the workpiece. This can promote extension of the cracks in the outer circumferential region of the workpiece in the main processing step. As a result, splitting-off of a substrate from the workpiece in a splitting-off step becomes easy. In addition, the probability of occurrence of large chipping in the outer circumferential region of the workpiece in this splitting-off can be reduced.