Recycled Semiconductor on Insulator Substrate Defect Management
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Solution Overview
Problem
The recycling of donor substrates in the SmartCut™ method for fabricating Semiconductor on Insulator (SeOI) substrates results in defects due to thermal treatments, leading to substrates of lesser quality and limited use, as they can only undergo two SmartCut cycles and may have increased Bulk Micro Defects (BMD) depending on initial properties and temperature gradients.
Innovation Solution
A method where a layer of semiconducting material is formed on the donor substrate by epitaxy before recycling, with a weakened zone created within this layer, and the substrate is chosen to have low oxygen precipitate density and size, allowing for the formation of a high-quality epitaxied layer that is recycled as a receiver substrate for a second SeOI substrate, minimizing thermal treatments and optimizing quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the donor substrate is recycled as receiver substrate after SmartCut cycles, then the number of thermal treatments is reduced, but the substrate still develops Bulk Micro Defects (BMD) due to initial thermal treatments
Solution Approach 1:
A sacrificial layer is formed on the donor substrate before the SmartCut process. This layer is specifically designed to be removed during recycling, taking with it the BMD defects generated during thermal treatments. The sacrificial layer acts as a buffer that protects the underlying substrate from defect propagation in subsequent recycling cycles.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the sacrificial layer (composition, thickness, defect density) to optimize its ability to trap and remove BMD defects. By controlling the layer's parameters, the system achieves effective defect management while maintaining substrate reusability.
2Manufacturing precision
If polishing is performed to remove damaged material from recycled substrates, then surface quality is improved, but a significant thickness of material is removed
Solution Approach 1:
The sacrificial layer is formed in advance with sufficient thickness to compensate for the material that will be removed during polishing. This preliminary action ensures that after polishing removes the damaged surface layer and BMD defects, enough healthy material remains to maintain the required substrate thickness for subsequent SmartCut cycles.
Solution Approach 2:
The sacrificial layer serves as an intermediary between the damaged substrate surface and the healthy bulk material. It provides a controlled zone that can be selectively removed through polishing, separating the harmful surface defects from the useful bulk material underneath.
3Productivity
If the donor substrate undergoes multiple SmartCut cycles, then substrate utilization is maximized, but the density and size of Bulk Micro Defects increase
Solution Approach 1:
The sacrificial layer is deliberately designed to be discarded during the recycling process through polishing. By removing this layer that contains accumulated BMD defects, the substrate is recovered in a cleaner state, enabling multiple recycling cycles while maintaining quality standards. The sacrificial layer acts as a disposable component that protects the valuable underlying substrate.
Solution Approach 2:
The patent controls the thickness and composition parameters of the sacrificial layer to ensure it can accommodate defect accumulation over multiple cycles. By adjusting these parameters, the system optimizes the balance between substrate reusability and defect management, allowing for controlled multiple recycling operations.
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 enhances the quality of recycled substrates by reducing defects and enabling the use of substrates for multiple SmartCut cycles, ensuring compliance with electronic component specifications and maintaining high-quality epitaxied semiconducting material, thus improving the overall quality of SeOI substrates.
Implementation Method 1
Oxidation of the donor substrate 10 or receiver substrate 30 to form an oxide layer 20
Implementation Method 2
Ion implantation in the donor substrate 10 to form a weakened zone 12
Implementation Method 3
Bonding of the donor substrate 10 onto the receiver substrate 30, the oxide layer 20 being located at the interface
Implementation Method 4
Fracturing the donor substrate 10 in the weakened zone 12 and transfer of a layer 11 from the donor substrate 10 to the receiver substrate 30
Implementation Method 5
a layer of semiconducting material is formed on the donor substrate by epitaxy
Data Source
AI summary
A method for fabricating a substrate of the semiconductor on insulator type by forming an epitaxial layer of semiconducting material on a donor substrate having oxygen precipitates with a density of less than 1010/cm3 or a mean size of less than 500 nm, forming an oxide layer on either a donor or receiver substrate, implanting atomic species in the donor substrate to form a weakened zone in the epitaxial layer, bonding the donor and receiver substrates together, with the oxide layer present at the bonding interface, fracturing the donor substrate in the weakened zone to transfer a layer of the donor substrate to the receiver substrate with the transferred layer including the epitaxial layer, and recycling the remainder of the donor substrate to form a receiver substrate for fabrication of a second semiconductor on insulator type substrate.