Single-Crystal Silicon Substrate Splitting via Internal Laser Separation
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Solution Overview
Problem
The existing method of cutting single-crystal silicon substrates using a wire saw results in significant material wastage and surface irregularities, leading to low productivity due to the large cutting allowance and formation of minute recesses and protrusions, which necessitate additional processing steps like lapping and polishing.
Innovation Solution
A manufacturing method that forms separation layers inside the workpiece using a laser beam with a specific wavelength, allowing for precise splitting of the substrate along specific crystal planes, reducing material wastage and improving surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a wire saw is used to cut substrates from an ingot, then the cutting process is simple and direct, but the cutting allowance is large (approximately 300 μm) and material wastage is significant (approximately 1/3 of the ingot material is discarded)
Solution Approach 1:
The patent replaces the mechanical wire saw cutting system with a laser-based processing system. The laser beam irradiates the ingot to form modified parts and cracks along specific crystal planes, enabling precise separation without the need for mechanical contact. This substitution eliminates the large cutting allowance (approximately 300 μm) required by wire saws and reduces material wastage from approximately 1/3 to a minimal amount, while maintaining manufacturing simplicity through automated laser control
Solution Approach 2:
The patent utilizes changes in the physical and chemical parameters of the single-crystal silicon material by irradiating it with a laser beam. The laser energy modifies the crystal structure along specific planes (such as {111} planes), creating controlled modified parts and cracks. By controlling the laser irradiation parameters (power, speed, pattern), the process achieves precise separation with minimal material removal, transforming the cutting process from mechanical removal to controlled material modification
2Ease of manufacture
If a wire saw is used to cut substrates from an ingot, then the cutting operation is straightforward, but minute recesses and protrusions are formed on the substrate surface requiring additional planarization steps (lapping, etching, and/or polishing)
Solution Approach 1:
The patent replaces mechanical wire saw cutting with laser-based separation that exploits the crystallographic properties of silicon. The laser irradiation creates modified parts and cracks that propagate along specific crystal planes, producing separation surfaces that inherently maintain the crystal structure integrity. This eliminates the mechanical contact that causes surface damage, recesses, and protrusions, thereby eliminating or significantly reducing the need for subsequent planarization steps while keeping the process straightforward through automated laser control
Solution Approach 2:
The patent performs preliminary action by using laser irradiation to pre-form modified parts and cracks along the desired separation planes before actual substrate separation. This preliminary laser treatment prepares the material by creating controlled modification zones that guide crack propagation along specific crystal planes, ensuring that the separation occurs cleanly without creating surface irregularities that would require additional planarization processing
3Device complexity
If a wire saw is used to cut substrates from an ingot, then the process requires fewer specialized equipment, but the productivity is low due to significant material discard and additional planarization processing
Solution Approach 1:
The patent replaces mechanical wire saw cutting with a laser-based system that integrates multiple functions into a single processing step. The laser system not only separates the substrates but also simultaneously creates the separation surfaces with high precision, eliminating the need for subsequent lapping, etching, and polishing operations. Although the laser equipment is more complex than a wire saw, the consolidation of cutting and planarization functions into one process dramatically improves productivity by eliminating material wastage (from 1/3 to minimal) and reducing the total number of processing steps
Solution Approach 2:
The patent merges the functions of substrate separation and surface planarization into a single laser processing operation. The laser beam simultaneously creates the separation cracks and produces smooth separation surfaces by exploiting crystal plane properties, combining what were previously distinct mechanical cutting and planarization steps into one integrated process. This merging of functions eliminates the need for multiple separate operations and significantly improves manufacturing efficiency
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 minimizing material discard and improving surface planarity, thus overcoming the limitations of wire saw cutting.
Implementation Method 1
a first laser beam irradiation step of relatively moving the workpiece and a focal point of a laser beam with such a wavelength as to be transmitted through the single-crystal silicon along the first direction
Implementation Method 2
forming separation layers including modified parts and cracks that extend from the modified parts inside the workpiece
Data Source
AI summary
There is provided a manufacturing method of a single-crystal silicon substrate by which the substrate is manufactured from a workpiece composed of single-crystal silicon manufactured in such a manner that a specific crystal plane included in the crystal planes {100} is exposed in each of a front surface and a back surface. The manufacturing method includes a separation layer forming step of forming separation layers including modified parts and cracks that extend from the modified parts inside the workpiece and a splitting-off step of splitting off the substrate from the workpiece with use of the separation layers as the point of origin after the separation layer forming step is executed. In the separation layer forming step, the separation layers are formed inside the workpiece composed of the single-crystal silicon by using a laser beam with such a wavelength as to be transmitted through the single-crystal silicon.