SiC Wafer Laser Pulse Splitting for Low-Loss Separation Layers
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Solution Overview
Problem
Conventional methods for manufacturing silicon carbide (SiC) wafers from ingots result in low productivity and significant material wastage, with only about 30% of the ingot being utilized, while existing pulsed laser methods require additional processing steps like grinding and lapping, leading to inefficiencies.
Innovation Solution
A laser processing machine that employs a pulsed laser beam with a splitter and delay unit to form a separation layer within the SiC ingot, dissociating SiC into silicon and carbon, allowing for efficient wafer separation with reduced material loss by controlling the peak energy per pulse and forming strip-shaped separation zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a pulsed laser beam with focal point positioned inside the SiC ingot is used to form modified layers as separation starting interfaces, then the amount of SiC wafer that can be manufactured from the ingot is increased, but additional grinding and lapping processing is required to remove the modified layers, resulting in poor productivity
Solution Approach 1:
The invention changes the parameter of laser pulse energy by splitting the pulsed laser beam into multiple sub-pulses with delayed timing. This parameter modification allows the laser to dissociate SiC into Si and C without forming excessive modified layers that would require additional mechanical processing, thereby resolving the contradiction between increasing wafer quantity and maintaining productivity
Solution Approach 2:
The invention applies periodic pulsed laser irradiation with specific pulse intervals and delay timing between split pulses. This periodic action with controlled timing enables cumulative dissociation of SiC into Si and C at the focal point, forming separation layers without creating harmful modified layers, thus improving both wafer quantity and productivity
2Reliability
If the pulsed laser beam energy is increased to effectively dissociate SiC into Si and C, then the separation layer formation is improved, but excessive energy may cause significant damage to the SiC ingot
Solution Approach 1:
The invention segments the high-energy pulsed laser beam into multiple lower-energy sub-pulses using a splitter unit. Each sub-pulse delivers controlled energy to dissociate SiC gradually, achieving reliable separation layer formation while avoiding the harmful effects of excessive single-pulse energy that would damage the SiC ingot
Solution Approach 2:
The delay unit introduces a time delay between split laser pulses, allowing heat dissipation and preventing cumulative thermal damage before the next pulse arrives. This beforehand cushioning protects the SiC ingot from excessive energy damage while maintaining effective dissociation, resolving the contradiction between separation quality and damage prevention
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 solution enhances productivity by reducing material wastage and improving the efficiency of SiC wafer production, allowing for the effective dissociation of SiC into silicon and carbon without significant damage, thereby increasing the yield of usable wafers from a given ingot.
Implementation Method 1
SiC is dissociated into Si and C to form a separation layer
Data Source
AI summary
A laser oscillation unit of a laser processing machine for manufacturing a SiC wafer from a SiC ingot includes a seed laser that emits a pulsed laser beam at predetermined pulse intervals, a splitter unit that splits the pulsed laser beam emitted by the seed laser, into at least a first pulsed laser beam and a second pulsed laser beam, a delay unit that delays one of the first pulsed laser beam and the second pulsed laser beam, a merger unit that merges the first pulsed laser beam and the second pulsed laser beam on a downstream side of the delay unit, and an amplifier arranged on a downstream side of the merger unit. A manufacturing method of a SiC wafer from a SiC ingot is also disclosed.