Donor Substrate Residue Preparation for Flat Bonding Reuse
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Solution Overview
Problem
The existing methods for preparing donor substrates using the Smart Cut™ technology result in bonding defects due to thermal expansion coefficient differences between the thick layer and the final support, leading to curvature and incomplete transfer of the thin layer, which worsens with recycling, making multiple use of the substrate economically undesirable.
Innovation Solution
A method involving the removal of the peripheral ring by grinding, followed by chemical-mechanical polishing to smooth the main surface, and ion etching to reduce the elevation of the peripheral zone, ensuring the residue can be reused multiple times without significant quality degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the donor substrate is reused multiple times through conventional reconditioning methods, then productivity is improved, but manufacturing precision deteriorates due to bonding defects and surface irregularities
Solution Approach 1:
The method performs preliminary actions by removing the peripheral ring and processing the main surface before the bonding defect can propagate. By proactively eliminating the elevated peripheral zone and surface defects through grinding and polishing, the substrate is prepared in advance to prevent bonding wave disturbances, thereby maintaining manufacturing precision across multiple reuse cycles
Solution Approach 2:
The method extracts and removes the problematic peripheral ring from the donor substrate. By separating and eliminating the elevated peripheral zone that causes bonding wave disturbances, the core functional area of the substrate is protected from defect propagation, enabling consistent thin layer transfer quality throughout the substrate's operational life
2Ease of manufacture
If the peripheral ring is not removed, then ease of manufacture is improved, but reliability deteriorates due to bonding defects at the edges
Solution Approach 1:
The method converts the harmful elevated peripheral ring into a beneficial process step. By intentionally removing and processing the peripheral zone, the method eliminates the source of bonding defects and surface irregularities. What was originally a problematic feature (the elevated ring) becomes the target of a corrective process that improves overall substrate reliability for reuse
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
The method effectively reduces bonding defects and allows the donor substrate to be reused multiple times, maintaining the quality of the transferred thin layer, even after several cycles, by ensuring a flat and smooth surface for molecular adhesion.
Implementation Method 1
The removal and transfer steps are implemented by way of the Smart Cut technology. The steps of removing and transferring the thin layer comprise introducing light species into the donor substrate, in this case into the thick layer of the composite donor substrate, through a face (or surface), called main face, of this substrate in order to form an embedded fragile plane.
Implementation Method 2
In a subsequent step, the donor substrate is assembled on the final support via its main surface, and heat treatment is applied to the assembly, optionally supplemented by the application of mechanical forces, in order to detach the thin layer at the fragile plane and transfer it onto the final support. The thick layer and the intermediate support have different thermal expansion coefficients, the composite donor substrate tends to have a curvature conferring a generally convex shape thereto
Implementation Method 3
The method comprises: a first step of removing at least part of the peripheral ring
Implementation Method 4
a second step of processing the main surface of the residue aiming to remove a surface layer
Implementation Method 5
a third step, after the second step, of ion etching grinding the peripheral zone of the main surface of the residue, the third grinding step aiming to reduce the elevation of the peripheral zone
Data Source
AI summary
A method is used for preparing the residue of a donor substrate, the residue comprising, on a peripheral zone of a main face, a peripheral ring. The method comprises: a first step of removing at least part of the peripheral ring; a second step of processing the main face of the residue aiming to remove a surface layer; a third step, after the second step, of grinding the peripheral zone of the main face of the residue, the third grinding step aiming to reduce the elevation of the peripheral zone.