Semi-Insulating SiC Substrate Transfer for Low-Loss III-N Epitaxy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for manufacturing substrates for epitaxial growth of III-N alloys face challenges with semi-insulating SiC substrates, including high costs, limited size, and significant RF losses and heat dissipation issues, particularly for high-power and high-frequency applications.
Innovation Solution
A method involving the transfer of a monocrystalline SiC layer onto a recipient substrate with a high electrical resistivity, followed by epitaxial growth of a semi-insulating SiC layer, which allows for the creation of a substrate with improved heat dissipation and minimized RF losses, using a temporary support to orient the silicon face optimally and avoiding thermal barriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If semi-insulating SiC substrates are used for epitaxial growth of III-N alloys, then good heat dissipation is achieved, but the substrates are expensive and limited in size
Solution Approach 1:
The substrate structure is segmented into multiple functional layers: a large-area polycrystalline SiC substrate for heat dissipation and electrical isolation, and a thin transferred monocrystalline SiC layer for high-quality epitaxial growth. This segmentation allows each layer to fulfill its specific function optimally while overcoming the limitations of using bulk semi-insulating SiC substrates.
Solution Approach 2:
The invention uses a composite substrate structure combining polycrystalline SiC and monocrystalline SiC layers. The polycrystalline SiC provides mechanical support, thermal management, and electrical isolation, while the monocrystalline SiC layer provides the necessary crystalline quality for low-defect epitaxial growth of III-N alloys.
2Ease of manufacture
If silicon substrates are used instead of SiC, then manufacturing costs are reduced and large substrates are available, but RF propagation losses increase and heat dissipation decreases
Solution Approach 1:
Different regions of the substrate structure have different material properties optimized for their specific functions. The polycrystalline SiC substrate provides thermal and electrical properties, while the thin monocrystalline SiC layer provides the local crystalline quality needed for low-loss RF performance in the active device regions.
3Ease of manufacture
If composite structures with single-crystal SiC on polycrystalline SiC are used, then cost is reduced and large substrates are available, but thermal barriers form at the interface
Solution Approach 1:
The invention removes the problematic intermediate silicon oxide layer that forms in conventional composite structures. By using direct bonding between monocrystalline and polycrystalline SiC layers without oxidation, the thermal barrier is eliminated and direct thermal contact is maintained across the interface.
4Ease of manufacture
If heteroepitaxy is performed on substrates with large lattice parameter differences, then crystalline defects and mechanical stresses increase
Solution Approach 1:
A thin layer of monocrystalline SiC is transferred to the polycrystalline SiC substrate before epitaxial growth of the III-N alloys. This preliminary action creates a high-quality crystalline template that minimizes lattice mismatch effects and reduces defect propagation during subsequent epitaxial growth.
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 enables the production of substrates with high crystalline quality III-N alloy layers that minimize RF losses and maximize heat dissipation, facilitating the development of high-power and high-frequency electronic devices.
Implementation Method 1
implanting ionic species in the donor substrate so as to form a weakening zone delimiting a thin layer of monocrystalline SiC to be transferred
Implementation Method 2
epitaxial growth of a layer (30) of semi-insulating SiC having a thickness greater than 1 μm on the thin layer of SiC
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
The invention relates to a method for producing a substrate for the epitaxial growth of a gallium-based III-N alloy layer, comprising the following successive steps: - providing a donor substrate (10) of single-crystal silicon carbide; - implanting ionic species in the donor substrate (10) so as to form an embrittlement zone (12) defining a thin film (11) of single-crystal SiC to be transferred; - bonding the donor substrate (10) onto a first receiving substrate (20) via a bonding layer (21); - detaching the donor substrate (10) along the embrittlement zone (12) so as to transfer the thin film (11) of SiC onto the first receiving substrate (20); - epitaxially growing a layer (30) of semi-insulating SiC having a thickness greater than 1 µm on the thin film (11) of SiC; - bonding the layer (30) of semi-insulating SiC onto a second receiving substrate (40), said second receiving substrate (40) having a high electrical resistivity; - removing at least a portion of the bonding layer (21) so as to detach the first receiving substrate (20); - removing the transferred thin film (11) of single-crystal SiC, so as to expose the semi-insulating SiC layer (30).