Laser Ingot Separation with Region-Specific Irradiation Control
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Solution Overview
Problem
The existing methods for manufacturing substrates from semiconductor ingots, such as those made of single-crystal SiC, face challenges due to non-uniform dopant concentrations leading to variations in laser beam absorption, resulting in irregularities in the separation layer and increased costs due to kerf loss and substrate planarization.
Innovation Solution
A laser processing method and machine that evaluate the optical characteristics of each region on the ingot, set specific irradiation conditions for the laser beam, and form a separation layer inside the ingot, allowing for uniform cleavage and reducing substrate irregularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a laser beam is irradiated under fixed conditions to form a separation layer, then the processing speed is maintained, but the separation layer becomes non-uniform due to varying dopant concentrations in different regions
Solution Approach 1:
The patent applies dynamics by making the laser irradiation conditions variable rather than fixed. The control unit dynamically adjusts irradiation parameters (such as power, speed, or pulse duration) based on real-time optical characteristic data of different regions. This allows the processing to adapt to varying dopant concentrations, maintaining both processing speed and separation layer uniformity across the ingot.
Solution Approach 2:
The patent changes physical parameters of the laser irradiation process based on the optical characteristics of different regions. By measuring optical characteristics (which correlate with dopant concentration) and adjusting irradiation parameters accordingly, the system achieves uniform separation layer formation despite non-uniform material composition. This parameter adaptation resolves the contradiction between fixed processing conditions and variable material properties.
2Loss of time
If the ingot is irradiated with a laser beam to form a separation layer, then substrate manufacturing time is reduced, but substrate surface irregularities increase due to non-uniform dopant distribution
Solution Approach 1:
The patent applies preliminary action by measuring the optical characteristics of different regions before laser irradiation. This pre-assessment of dopant distribution allows the system to plan and execute region-specific irradiation parameters in advance, ensuring uniform separation layer formation and minimizing surface irregularities while maintaining fast processing speeds.
Solution Approach 2:
The system changes laser irradiation parameters based on pre-measured optical characteristics of different regions. This targeted parameter adjustment ensures that each region receives appropriate energy input, preventing over- or under-processing that would cause surface irregularities, while still maintaining overall processing efficiency.
3Strength
If a separation layer is formed in regions with high dopant concentration, then the separation layer becomes dense with few cracks, but cleavage becomes difficult and substrate quality deteriorates
Solution Approach 1:
The patent changes laser irradiation parameters specifically for high dopant concentration regions (identified by optical characteristic measurements). By adjusting parameters such as reducing power or increasing pulse duration in these regions, the system creates separation layers with appropriate crack density, enabling easy cleavage while maintaining overall layer integrity and producing flat substrate surfaces.
Solution Approach 2:
The patent applies local quality by treating different regions of the ingot differently based on their dopant concentrations. High dopant regions receive customized irradiation parameters to create separation layers with more cracks, while low dopant regions receive different parameters. This localized treatment ensures uniform cleavage characteristics across the entire substrate surface.
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 enables the formation of a uniform separation layer within the ingot, facilitating efficient cleavage and reducing substrate irregularities, thereby minimizing costs associated with kerf loss and substrate planarization.
Implementation Method 1
a laser processing method for forming a separation layer inside an ingot by using a laser beam of a wavelength having transmissivity for a material of the ingot
Implementation Method 2
a region having a high dopant concentration like the facet region has a high absorption rate of a laser beam, in other words, low transmissivity for a laser beam
Data Source
AI summary
A laser processing method for forming a separation layer inside an ingot by using a laser beam includes a manufacturing a substrate by separating a portion of the ingot, the portion being located on a side of one side of the ingot, then evaluating the substrate to acquire information on optical characteristics in each of a plurality of regions on the one side of the ingot, then setting, for every one of the plurality of regions, irradiation conditions for the laser beam with reference to the information, and then forming the separation layer inside the ingot by irradiating the ingot with the laser beam from the one side with a focal point at which the laser beam is focused inside of the ingot.