Laser Wafer Separation in Ingot for Low-Loss High-Throughput Slicing
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Solution Overview
Problem
The existing methods for manufacturing wafers from ingots result in high material wastage and low productivity due to the large wire width of wire saws and the inefficiency of processing ingots one by one using laser beams.
Innovation Solution
A method involving entire plane processing with a laser beam to form separation initiating points and cracks in monocrystalline ingots, allowing for simultaneous formation of multiple wafer layers at different depths, which are then indexed and separated using ultrasonic vibrations to increase throughput and reduce material loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wire saw is used to slice ingot into wafers, then cutting can be performed, but material wastage is high and productivity is low
Solution Approach 1:
The patent replaces the mechanical wire saw cutting system with a laser-based processing system. The laser beam forms separation initiating points and cracks within the ingot through optical energy, eliminating the need for mechanical contact and the associated material removal. This substitution enables precise control of the separation process while minimizing material wastage and increasing throughput by allowing parallel processing of multiple wafers simultaneously.
Solution Approach 2:
The patent applies preliminary action by forming separation initiating points and cracks within the ingot before actual separation occurs. The laser processing creates modified layers and initiation points that facilitate subsequent clean separation. This preliminary modification of the ingot structure enables efficient wafer release and reduces the force needed for separation, thereby minimizing material damage and wastage.
2Productivity
If laser beam processes ingot one by one, then material wastage is reduced, but throughput is low
Solution Approach 1:
The patent merges multiple laser processing operations into a single integrated system. Multiple focused spots are generated simultaneously from a single laser source, allowing parallel formation of separation initiating points at different depths within the same ingot. This combining of operations enables simultaneous processing of multiple wafer positions, dramatically increasing throughput while maintaining the material efficiency of laser-based processing.
Solution Approach 2:
The patent extends the processing from a single plane to three-dimensional space by forming focused spots at multiple depths within the ingot. The laser beam processes the ingot volume rather than just the surface, creating separation initiating points throughout the thickness of the ingot. This volumetric processing approach enables simultaneous preparation of multiple wafer separation planes, increasing throughput without sacrificing material efficiency.
3Productivity
If multiple focused spots are formed simultaneously, then throughput increases, but processing complexity increases
Solution Approach 1:
The patent achieves multi-functionality by using a single laser beam to perform multiple processing functions simultaneously. The same laser source generates multiple focused spots at different positions and depths, creating separation initiating points throughout the ingot volume. This universal approach eliminates the need for multiple separate processing systems while maintaining high throughput through parallel operation of multiple focused spots.
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 wafer manufacturing productivity by reducing material wastage and increasing throughput, enabling the efficient production of multiple wafers from a single ingot while maintaining high precision.
Implementation Method 1
a focused spot of a laser beam whose wavelength is transmittable through a material of the ingot is positioned within the ingot from the first surface side
Implementation Method 2
forming in the ingot separation initiating points including modified layers in a plane parallel to the first surface and cracks developed from the modified layers
Implementation Method 3
The separating step separates a wafer from the ingot along the separation initiating points, after the entire plane processing step has been carried out
Data Source
AI summary
A method of manufacturing a wafer includes an entire plane processing step and a separating step. The entire plane processing step repeats a separation initiating point forming step of, while positioning a focused spot of a laser beam within an ingot, moving the focused spot and the ingot relatively to each other along a predetermined processing feed direction, thereby forming in the ingot separation initiating points including modified layers in a plane parallel to a first surface of the ingot and cracks developed from the modified layers, and an indexing feed step of indexing-feeding the focused spot of the laser beam relatively to the ingot in a direction perpendicular to the processing feed direction. The separating step separates a wafer from the ingot along the separation initiating points.