Bonded SiC Wafer Structure for Reusing High-Stress Substrates
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Solution Overview
Problem
In semiconductor manufacturing, high-stress silicon carbide wafers adjacent to seed crystals are typically discarded, leading to increased waste costs and inefficiencies in epitaxial processes for RF and power devices.
Innovation Solution
A bonding wafer structure is developed using a support substrate with a bonding layer and a silicon carbide layer of low quality, where the silicon carbide layer is bonded directly onto the support substrate, reducing material and waste costs, and improving yield by utilizing a three-layer structure with specific thickness and dislocation characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low-quality silicon carbide wafers are discarded, then manufacturing quality is maintained, but material waste increases and cost rises
Solution Approach 1:
The patent converts the harmful effect of high stress and defects in low-quality silicon carbide wafers into a beneficial outcome by bonding these wafers to a support substrate. The support substrate absorbs and isolates the stress and defects, preventing them from affecting the final epitaxial product quality while enabling the reuse of previously discarded wafers, thus reducing material waste and cost
Solution Approach 2:
The patent segments the wafer system into two functional parts: a support substrate that bears the mechanical stress and a silicon carbide layer that provides the epitaxial growth surface. This segmentation allows the low-quality wafer to be used without compromising the quality of the final product, as the support substrate isolates the defects from the epitaxial process
2Loss of substance
If low-quality silicon carbide wafers are reused, then material cost is reduced, but manufacturing precision may deteriorate
Solution Approach 1:
The support substrate acts as an intermediary between the low-quality silicon carbide wafer and the epitaxial growth process. It compensates for the wafer's defects including bow and warp, providing a stable platform that ensures manufacturing precision is maintained even when using reused low-quality wafers
Solution Approach 2:
The patent changes the physical state and mechanical properties of the system by bonding the silicon carbide wafer to the support substrate. This bonding process alters the stress distribution and mechanical stability parameters, transforming a unstable, low-precision wafer into a stable configuration suitable for precise epitaxial manufacturing
3Stability of the object's composition
If a bonding layer is added to support the silicon carbide layer, then structural stability is improved, but device complexity increases
Solution Approach 1:
The bonding layer serves as an intermediary between the support substrate and the silicon carbide layer, providing a controlled interface that ensures stable bonding while managing thermal and mechanical properties. This intermediary layer enables the use of low-quality wafers by isolating their defects, justifying the added structural complexity
Solution Approach 2:
The patent creates a composite structure combining the support substrate, bonding layer, and silicon carbide layer. This composite material approach allows each layer to contribute its specific properties: the support substrate provides mechanical stability, the bonding layer provides interface control, and the silicon carbide layer provides epitaxial growth capability, achieving overall system stability that justifies the multi-layer complexity
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 bonding wafer structure achieves reduced material and waste costs, improved flatness, and enhanced yield for epitaxial processes, making it suitable for RF and power device manufacturing by effectively reusing low-quality silicon carbide wafers.
Implementation Method 1
the silicon carbide layer is bonded onto the bonding layer
Data Source
AI summary
A bonding wafer structure includes a support substrate, a bonding layer, and a silicon carbide (SiC) layer. The bonding layer is formed on a surface of the support substrate, and the SiC layer is bonded onto the bonding layer, in which a carbon surface of the SiC layer is in direct contact with the bonding layer. The SiC layer has a basal plane dislocation (BPD) of 1,000 ea/cm2 to 20,000 ea/cm2, a total thickness variation (TTV) greater than that of the support substrate, and a diameter equal to or less than that of the support substrate. The bonding wafer structure has a TTV of less than 10 μm, a bow of less than 30 μm, and a warp of less than 60 μm.