Useful Layer Transfer by Stress-Controlled Splitting During Annealing
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Solution Overview
Problem
The existing process for transferring a useful layer to a carrier substrate in microelectronics lacks reproducibility in morphological surface properties, such as surface roughness and thickness uniformity, due to variability in implantation and annealing conditions, affecting production yields.
Innovation Solution
A process involving a donor substrate with a buried weakened plane, where a predetermined stress is applied during annealing to initiate a self-sustained splitting wave, ensuring consistent weakening and reproducible transfer of the useful layer to the carrier substrate, with controlled mechanical load and temperature management to achieve desired morphological properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a heat treatment is applied to weaken the buried weakened plane, then the useful layer can be transferred, but the morphological surface properties (roughness, thickness uniformity) become non-reproducible from one wafer to the next
Solution Approach 1:
The patent applies a predetermined stress during the annealing process, which changes the physical parameters of the buried weakened plane. This stress application modifies the annealing conditions to achieve a constant level of weakening, ensuring reproducible splitting behavior and consistent morphological surface properties across wafers.
Solution Approach 2:
The predetermined stress is applied during the annealing process to pre-establish the correct level of weakening in the buried weakened plane before the actual splitting occurs. This preliminary action ensures that when splitting is initiated, the conditions are already optimized for reproducible results.
2Manufacturing precision
If additional finishing steps (etches or surface-smoothing heat treatments) are carried out after transfer, then the specifications can be met, but the process complexity increases and not all wafers achieve required specifications
Solution Approach 1:
The patent performs the surface preparation action during the annealing process itself by applying predetermined stress to achieve the correct level of weakening. This preliminary action ensures that the useful layer is transferred with already-optimized surface properties, eliminating or reducing the need for subsequent finishing steps.
3Length of moving object
If the useful layer thickness is reduced to lower than 50 nm, then advanced semiconductor device architecture is enabled, but the requirements for thickness uniformity and surface quality become much more stringent
Solution Approach 1:
By applying predetermined stress during annealing, the patent achieves a controlled and reproducible level of weakening in the buried weakened plane. This parameter change ensures that even for very thin useful layers below 50 nm, the splitting process produces consistent thickness uniformity and surface quality that meets stringent specifications.
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 ensures high reproducibility of low surface roughness and high thickness uniformity for the transferred useful layers, meeting stringent specifications for semiconductor devices by initiating the splitting wave at a constant level of weakening, independent of variations in implantation or annealing conditions.
Implementation Method 1
forming a buried weakened plane 2 by implanting light species into a donor substrate 1
Implementation Method 2
applying a heat treatment to the bonded structure 5 in order to weaken the buried weakened plane
Implementation Method 3
initiating a splitting wave by means of an energy pulse applied at the level of the buried weakened plane 2, with self-sustained propagation of the splitting wave
Data Source
AI summary
A method for transferring a useful layer from a donor substrate to a carrier substrate comprises: a) providing the donor substrate, the donor substrate including a buried weakened plane; b) providing the carrier substrate; c) joining the donor substrate to the carrier substrate to form a bonded structure; and d) annealing the bonded structure in order to increase the level of weakening of the buried weakened plane. A predetermined stress is applied to the buried weakened plane during the annealing for a period of time, the predetermined stress being selected so as to initiate the splitting wave once a given level of weakening has been reached. At the end of the period of time, the given level of weakening having been reached, the predetermined stress causes initiation and self-sustained propagation of the splitting wave along the buried weakened plane, resulting in the useful layer being transferred to the carrier substrate.