Single-Crystal Silicon Substrate Splitting via Laser Separation Layers
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Solution Overview
Problem
The existing method of cutting single-crystal silicon substrates from ingots using a wire saw results in significant material wastage and surface irregularities, leading to low productivity due to a large cutting allowance and substrate warpage.
Innovation Solution
A manufacturing method involving the use of a laser to form separation layers inside the ingot, allowing for precise splitting of the substrate with reduced material loss and improved surface planarity, by irradiating the ingot with a laser beam to create cracks along specific crystal planes, thereby facilitating the separation of substrates with minimal waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a wire saw is used to cut substrates from an ingot, then substrates can be manufactured, but material wastage is significant (approximately 1/3 of the ingot material is discarded) and productivity is low
Solution Approach 1:
The patent replaces the mechanical wire saw cutting system with a laser-based separation system. The laser beam irradiates the ingot to form separation layers along crystal planes, eliminating the need for mechanical cutting. This substitution reduces material wastage from approximately 1/3 to minimal amounts while improving manufacturing efficiency and productivity.
Solution Approach 2:
The patent utilizes the specific crystal orientation parameters of the single-crystal silicon ingot (with crystal plane {100} exposed on front and back surfaces) and directs the laser beam at specific angles relative to the crystal orientation. By controlling the laser irradiation parameters (wavelength, angle, intensity) according to the crystal structure, the method achieves precise separation with minimal material loss.
2Manufacturing precision
If a wire saw is used to cut substrates, then substrates can be obtained, but surface irregularities are formed and warpage occurs, requiring additional planarization processes
Solution Approach 1:
The laser-based separation method replaces mechanical cutting, eliminating the contact forces and vibrations that cause surface irregularities and warpage. The laser energy selectively modifies the crystal structure along separation layers without mechanical stress, producing smooth, flat surfaces that require minimal or no additional planarization.
Solution Approach 2:
The laser separation process performs the separation action before any substrate handling or processing occurs. By creating the separation layers while the ingot is in its original position and orientation, the method prevents the formation of surface irregularities and warpage that would otherwise require corrective planarization processes.
3Loss of substance
If laser beam irradiation is used to form separation layers, then material loss is reduced and surface quality is improved, but the process requires precise control of laser parameters and crystal orientation
Solution Approach 1:
The patent specifies particular laser parameters (wavelength suitable for transmitting through single-crystal silicon, specific irradiation angles relative to crystal orientation) to achieve effective separation. By optimizing these parameters, the system achieves high precision separation with minimal material loss while maintaining manageable system complexity through well-defined operational parameters.
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 productivity of single-crystal silicon substrates by reducing material discard and improving surface quality through precise separation and planarization, compared to traditional wire saw methods.
Implementation Method 1
irradiating the single-crystal silicon ingot with a laser beam with such a wavelength as to be transmitted through single-crystal silicon from the side of the front surface while moving a focal point of the laser beam and the single-crystal silicon ingot relative to each other along a first direction
Implementation Method 2
form a separation layer in a linear region along the first direction inside the single-crystal silicon ingot
Data Source
AI summary
After separation layers are formed inside a single-crystal silicon ingot, a single-crystal silicon substrate is split off from the single-crystal silicon ingot with use of these separation layers as the point of origin. This can improve the productivity of the single-crystal silicon substrate compared with the case of manufacturing the single-crystal silicon substrate from the single-crystal silicon ingot by a wire saw.