Substrate Separation via Stress Corrosion and Peripheral Damage
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Solution Overview
Problem
Existing methods struggle to separate substrates with high binding energies without damaging or fracturing them, particularly in applications like silicon-on-insulator structures where the fracture energy is high, making it difficult to initiate separation along the desired interface.
Innovation Solution
A method involving the selection of an interface sensitive to stress corrosion, where a peripheral region with reduced fracture energy is created by localized damage, allowing a blade to initiate separation, and a fluid is applied to reduce the fracture energy further, facilitating separation without substrate damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a blade is inserted to separate substrates with high binding energy, then separation can be initiated, but the substrates may break or be damaged due to high fracture energy
Solution Approach 1:
The patent applies local quality by creating a peripheral region with modified properties (reduced fracture energy) at the separation interface. This localized modification allows the blade to initiate separation safely at the periphery while the central region maintains its original properties. The peripheral region acts as a controlled entry point that prevents uncontrolled fracture propagation into the substrate interior.
Solution Approach 2:
The patent employs preliminary action by pre-damaging the separation interface in the peripheral region before blade insertion. This pre-weakening step reduces the fracture energy locally, creating favorable conditions for safe blade insertion and separation initiation. The preliminary damage prepares the interface to accommodate the blade without causing substrate breakage.
2Strength
If the fracture energy at the separation interface is high, then substrate strength is maintained, but separation becomes difficult to initiate without damage
Solution Approach 1:
The patent creates a spatial variation in fracture energy by modifying only the peripheral region while leaving the central region unchanged. This local quality approach maintains high substrate strength in the central area while creating a low-fracture-energy zone at the periphery for easy separation initiation. The blade enters through the modified peripheral region where fracture energy is reduced, avoiding the need to compromise overall substrate strength.
3Reliability
If the peripheral region is damaged to reduce fracture energy, then separation can be initiated safely, but the interface structure is modified
Solution Approach 1:
The patent accepts localized structural modification in the peripheral region as a necessary trade-off for safe separation. The damage is confined to a limited peripheral zone and does not affect the central region or the overall substrate integrity. This localized modification creates a controlled entry point that enables reliable separation while minimizing impact on the global interface structure.
Solution Approach 2:
The patent segments the separation interface into two distinct zones: a peripheral region with modified properties for safe blade insertion and a central region with original properties for maintaining substrate strength. This segmentation allows the peripheral zone to be damaged or modified without affecting the central zone, enabling controlled separation initiation while preserving the overall interface structure.
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
Enables safe and effective separation of substrates with high binding energies by reducing the fracture energy in the peripheral region, preventing substrate breakage and ensuring separation occurs along the chosen interface with minimal risk of damage.
Implementation Method 1
the insertion of a blade between said substrates and the application by said blade of a force to separate the two substrates
Implementation Method 2
an interface sensitive to stress corrosion is chosen for the separation, that is to say to the combined action of said separation force and of a fluid capable of breaking the siloxane bonds (Si-O-Si) present at said interface
Implementation Method 3
a fluid is applied in the interval between said separated substrates while continuing to insert said blade, so as to reduce the fracture energy of the interface chosen by stress corrosion
Data Source
Figure 1~2B
Figure 3A~5
AI summary
The invention relates to a method for separating at least two substrates (S1, S2), which form part of a structure (S) comprising at least two separation interfaces (I1, I2) extending parallel to the main faces of the structure, along an interface (I1) selected from said interfaces, at least one of said two substrates being intended for use in electronics, optics, optoelectronics and/or photovoltaics. The separation is performed by inserting a blade (B) between the substrates (S1, S2) and, by means of said blade, applying a force that separates the two substrates. The method is characterised in that it comprises steps consisting in: for the separation, selecting an interface (I1) that is susceptible to stress corrosion cracking, i.e. under the combined action of the separation force and a fluid that can break the siloxane bonds (Si-O-Si) present at the interface (I1); prior to the insertion of the blade, damaging at least part of a peripheral region (R1) of the selected interface (I1), containing the region in which the blade (B) is inserted, such that the impact strength of said peripheral region (R1) is lower than that of the other interfaces in the blade-insertion region, thereby allowing the separation of the substrates (S1, S2) to be initiated along the selected interface (I1) in the damaged region (R1); and applying a fluid in the space between the separated substrates (S1, S2), while continuing to insert the blade, such as to reduce the impact strength at the selected interface (I1) by means of stress corrosion cracking.