Single-Crystal Silicon Substrate Peeling With Controlled Crack Layers
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Solution Overview
Problem
The existing methods for manufacturing single crystal silicon substrates using a wire saw result in significant material waste and low productivity due to large slicing margins and surface irregularities, with the use of laser peeling layers leading to cracks that increase disposal amounts.
Innovation Solution
A manufacturing method that forms peeling layers with controlled crack propagation by alternating laser beam irradiation steps along specific crystal orientations, adjusting power and depth to minimize material loss during substrate separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a wire saw is used to slice substrates from an ingot, then substrates can be manufactured, but a large slicing margin (approximately 300 μm) is required resulting in significant material waste
Solution Approach 1:
The patent replaces the mechanical wire saw slicing process with a laser-based peeling layer formation process. Laser beams are used to create modified portions and induce cracks that propagate along crystal planes, enabling substrate separation without mechanical contact. This substitution eliminates the need for large slicing margins and the associated material waste.
Solution Approach 2:
The laser processing induces localized phase transitions in the single crystal silicon, creating modified portions through controlled heating and cooling cycles. These phase transitions lead to crack propagation along specific crystal planes, enabling clean separation without mechanical force and minimizing material loss.
2Productivity
If a wire saw is used to slice substrates, then substrates can be produced, but fine irregularities are formed on surfaces requiring additional planarization processing
Solution Approach 1:
The mechanical wire saw slicing process is replaced with laser-induced crack propagation. The laser creates controlled modifications that result in clean, planar separation surfaces without the mechanical contact-induced irregularities. This eliminates the need for subsequent lapping, etching, and polishing operations.
3Ease of manufacture
If a wire saw is used to slice substrates, then substrates can be manufactured, but the substrate becomes curved (warp is produced) requiring planarization
Solution Approach 1:
The patent replaces mechanical slicing with laser-based peeling layer formation. The laser-induced crack propagation occurs along crystal planes without applying mechanical stress that would cause warping. This results in flat, warp-free substrates that maintain their shape without requiring additional planarization processing.
4Ease of manufacture
If split laser beams are applied along the [011] crystal orientation, then peeling layers can be formed, but thick peeling layers are formed increasing the amount of material to be disposed of
Solution Approach 1:
The patent optimizes the laser processing parameters including beam orientation, power, pulse duration, and focal depth to control crack propagation. By adjusting these parameters, the peeling layer thickness is minimized while still achieving effective substrate separation, thereby reducing material waste.
Solution Approach 2:
The laser processing is applied in a controlled manner to create just enough modification to initiate crack propagation along the desired path. The processing is stopped once the peeling layer is formed, avoiding excessive material removal while ensuring complete separation.
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 reduces material waste and enhances productivity by forming thinner peeling layers, allowing for more efficient substrate production from a single crystal silicon ingot.
Implementation Method 1
forming, inside the workpiece, peeling layers that include modified portions and cracks propagating from the modified portions by relatively moving focal points, at which a plurality of split laser beams of a wavelength having transmissivity for the single crystal silicon are focused
Data Source
AI summary
A manufacturing method of a single crystal silicon substrate includes a peeling layer forming step of forming, inside a workpiece, peeling layers that include modified portions and cracks propagating from the modified portions, and a separation step of separating the substrate from the workpiece using the peeling layers as starting points. The peeling layer forming step has a first processing step of forming some of the modified portions in first regions that each extend along a first direction and are separated from one another in a second direction orthogonal to the first direction, and a second processing step of forming the remaining part of the modified portions and the cracks in second regions that each extend along the first direction and that are separated from one another in the second direction.