Thin Film Transfer via Roughened Bond Interface Crack Initiation
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Solution Overview
Problem
Existing thin film transfer methods using Smart Cut™ technology result in significant variability in surface roughness, both high and low frequencies, leading to degraded quality in the final stacked structure, particularly in SOI structures.
Innovation Solution
A transfer method involving a bonded assembly with a local unbonded area created by a predetermined rough zone on the substrate surfaces, initiated by a laser pulse generating only superficial melting, with a predetermined roughness, which is a laser beam, with a laser beam, to initiate a spontaneous separation, a thermal activation, leading to improved surface roughness and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If spontaneous separation is used in the buried brittle plane, then the thin film transfer is achieved, but significant variability in surface roughness occurs
Solution Approach 1:
The patent applies preliminary action by creating a local unbonded zone before the separation process. This unbonded zone, formed by roughening a specific area on the substrate surface, serves as a predetermined initiation point for crack propagation. By preparing this localized region in advance, the patent controls where separation begins, thereby reducing variability in surface roughness and improving the consistency of thin film transfer quality.
2Manufacturing precision
If local unbonded zone is created by topology (cavities and peaks), then separation is triggered and roughness is limited, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the surface roughness parameters in a localized area rather than creating complex topological features. Instead of forming cavities and peaks with specific geometries, the patent roughens a local area to create an unbonded zone. This approach controls separation initiation through surface texture parameters (roughness amplitude and distribution) rather than through complex structural topology, thereby achieving roughness control while maintaining relatively simple device 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
The method achieves consistent and low surface roughness in the transferred thin layer, reducing variability and eliminating dense zones of high roughness, resulting in improved quality of the final stacked structure.
Implementation Method 1
a predetermined roughness, which is a laser pulse generating only superficial melting, within the first 1 to 30 nanometers, of a material composing the donor substrate and/or the support substrate
Implementation Method 2
a laser pulse generating only superficial melting, within the first 1 to 30 nanometers, of a material composing the donor substrate and/or the support substrate
Implementation Method 3
The growth of microcracks in the buried brittle plane, through thermal activation, can lead to spontaneous separation along said plane
Implementation Method 4
this bonding is achieved through direct molecular adhesion, meaning without the use of adhesives: a bonding interface is thus established between the two bonded substrates
Data Source
Figure 1(A)~3a
Figure 3b~5
Figure 6~8a
AI summary
The invention relates to a method for transferring a thin film onto a support substrate, which comprises: providing a bonded assembly that comprises a donor substrate and the support substrate, assembled by direct bonding at their respective front faces, following a bonding interface, the bonded assembly having a local unbonded area within this bonding interface, the donor substrate further comprising a buried brittle plane; separating along the buried brittle plane, initiated at the local unbonded area after microcrack growth in said plane by thermal activation, the separation resulting in the transfer of a thin film from the donor substrate to the support substrate. The method is characterised in that the local unbonded area is generated solely by a roughened area, produced deliberately on at least one of the front faces of the donor and support substrates prior to assembly, free of topology and having a predetermined roughness with an amplitude of between 0.5 nm RMS and 60.0 nm RMS.