SiC Substrate Exfoliation for Reusable Low-Defect Epitaxial Layers
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Solution Overview
Problem
The high cost and defect-related yield loss in wide bandgap semiconductor devices are exacerbated by the expensive and complex process of fabricating SiC substrates, which contribute significantly to the final device cost and reliability issues, particularly in larger die sizes.
Innovation Solution
A method involving the use of a silicon carbide substrate with patterned carbon regions and epitaxial lateral overgrowth (ELO/MELO) to form a reusable substrate, allowing for the exfoliation and reuse of the substrate while maintaining low defect densities and reducing material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional SiC substrate fabrication process (vapor phase ingot growth, cropping, wire sawing, grinding, polishing) is used, then substrate quality is improved, but manufacturing cost increases and process complexity increases
Solution Approach 1:
The patent extracts and eliminates the need for traditional substrate fabrication steps (vapor phase ingot growth, cropping, wire sawing, grinding, polishing) by directly growing epitaxial layers on SiC seed crystals. This removes complex processing steps while maintaining substrate quality through direct epitaxial growth.
Solution Approach 2:
The patent uses disposable SiC seed crystals that are consumed during the epitaxial growth process. Instead of fabricating and reusing expensive substrates through complex processes, new seed crystals are used for each growth cycle, simplifying the overall manufacturing process.
2Reliability
If traditional SiC substrate fabrication process is used, then substrate quality is improved, but manufacturing cost increases
Solution Approach 1:
The patent extracts and eliminates the need for traditional substrate fabrication steps (vapor phase ingot growth, cropping, wire sawing, grinding, polishing) by directly growing epitaxial layers on SiC seed crystals. This removes complex processing steps while maintaining substrate quality through direct epitaxial growth.
Solution Approach 2:
The patent uses disposable SiC seed crystals that are consumed during the epitaxial growth process. Instead of fabricating and reusing expensive substrates through complex processes, new seed crystals are used for each growth cycle, simplifying the overall manufacturing process.
3Productivity
If larger die sizes are used to accommodate high current devices, then device performance is improved, but defect-related yield loss increases
Solution Approach 1:
The patent extracts and eliminates the need for traditional substrate fabrication steps (vapor phase ingot growth, cropping, wire sawing, grinding, polishing) by directly growing epitaxial layers on SiC seed crystals. This removes complex processing steps while maintaining substrate quality through direct 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 cost-effective production of high-quality semiconductor devices with reduced substrate contribution to the final die, enhancing yield and reliability by allowing the substrate to be reused multiple times.
Implementation Method 1
a laser is configured to heat the second material such that the plurality of silicon carbide regions in patterned layer are vaporized or partially vaporized
Implementation Method 2
a torque is applied to at least one of the reusable silicon carbide substrate or the at least one silicon carbide epitaxial layer to separate reusable silicon carbide substrate from the at least one silicon carbide epitaxial layer
Data Source
AI summary
A semiconductor substrate comprising a first epitaxial silicon carbide layer and a second silicon carbide epitaxial layer. At least one semiconductor device is formed in or on the second silicon carbide epitaxial layer. The semiconductor substrate is formed overlying a silicon carbide substrate having a surface comprising silicon carbide and carbon. An exfoliation process is used to remove the semiconductor substrate from the silicon carbide substrate. The carbon on the surface of the silicon carbide substrate supports separation. A portion of the silicon carbide substrate on the semiconductor substrate is removed after the exfoliation process. The surface of the silicon carbide substrate is prepared for reuse in subsequent formation of semiconductor substrates.