Silicon Substrate Separation Bands for Low-Waste Wafer Slicing
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Solution Overview
Problem
The existing methods for manufacturing Si substrates from Si ingots using inner diameter blades and wire saws result in low productivity due to high material wastage, with the cutting allowance being approximately 1/3 of the ingot.
Innovation Solution
A method involving the formation of a separation band using a laser beam with a wavelength transmissible to Si, where the focal point is moved in specific directions relative to the Si ingot's crystal planes to create a separation layer parallel to the (100) crystal plane, allowing for efficient separation of Si substrates without significant material loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If inner diameter blade or wire saw is used for cutting Si ingot, then Si substrate can be manufactured, but cutting allowance is large (approximately 1 mm) resulting in low productivity and high material wastage
Solution Approach 1:
The patent replaces the mechanical cutting system (inner diameter blade or wire saw) with a laser-based system. The laser beam forms a separation band inside the Si ingot by melting and evaporating material along a predetermined path, eliminating the need for mechanical contact and the associated large cutting allowances. This substitution directly reduces material wastage and improves productivity.
Solution Approach 2:
The patent performs preliminary action by forming a separation band inside the Si ingot before actual substrate separation. The laser creates a weakened path along the desired separation line, allowing subsequent easy separation with minimal material removal. This preliminary processing eliminates the need for large cutting allowances required by mechanical methods.
2Quantity of substance
If inner diameter blade or wire saw is used for cutting Si ingot, then Si substrate can be manufactured, but cutting allowance is large (approximately 1/3 of Si ingot) resulting in low material utilization
Solution Approach 1:
The patent replaces mechanical cutting with laser processing, which can create precise separation bands with minimal material removal. The laser beam selectively removes material only along the separation path, preserving the majority of the Si ingot for substrate production and significantly improving material utilization.
Solution Approach 2:
The patent changes the processing parameters from mechanical cutting (requiring large allowances for blade thickness and tool wear) to laser processing (where the separation band width can be precisely controlled by laser parameters). This parameter change enables much tighter tolerances and reduced material wastage.
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 approach enables the efficient manufacture of Si substrates by reducing material wastage and improving productivity, as the separation bands are formed in a manner that allows for easy separation and subsequent planarization of the substrates.
Implementation Method 1
a separation band forming step of forming a separation band through positioning a focal point of a laser beam with a wavelength having transmissibility with respect to Si to a depth equivalent to a thickness of the Si substrate to be manufactured from the flat surface and irradiating the Si ingot with the laser beam
Implementation Method 2
irradiating the Si ingot with the laser beam while relatively moving the focal point and the Si ingot in a direction <110> parallel to a cross line at which a crystal plane {100} and a crystal plane {111} intersect or a direction [110] orthogonal to the cross line
Data Source
AI summary
An Si substrate manufacturing method includes a separation band forming step of forming a separation band through positioning a focal point of a laser beam with a wavelength having transmissibility with respect to Si to a depth, equivalent to a thickness of an Si substrate to be manufactured, from a flat surface of an Si ingot and irradiating the Si ingot with the laser beam while relatively moving the focal point and the Si ingot in a direction <110> parallel to a cross line at which a crystal plane {100} and a crystal plane {111} intersect or a direction [110] orthogonal to the cross line, and an indexing feed step of executing indexing feed of the focal point and the Si ingot relatively in a direction orthogonal to a direction in which the separation band is formed.