SiC Crystal Substrate Surface Treatment for Low-Polycrystal Epitaxy
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Solution Overview
Problem
The existing methods for manufacturing SiC crystal substrates result in a high rate of polycrystal generation in SiC epitaxial films, which affects the quality and performance of the substrates.
Innovation Solution
A method involving chemical mechanical polishing followed by the application of a cluster of noble gas ions is used to reduce the rate of polycrystal generation, where the polishing process is optimized by controlling the abrasive grain size, load, and oxidizing agents, and the ion beam treatment removes foreign substances and oxide films, thereby minimizing chemical state changes on the substrate surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing methods are used for SiC crystal substrates, then production efficiency is maintained, but the rate of polycrystal generation in SiC epitaxial films is high
Solution Approach 1:
The patent applies preliminary actions by performing chemical mechanical polishing and gas cluster ion beam treatment on the SiC substrate before epitaxial film formation. These preliminary treatments modify the substrate surface state to suppress polycrystal generation during subsequent epitaxial growth, thereby improving manufacturing precision without significantly impacting productivity
Solution Approach 2:
The patent changes physical and chemical parameters of the substrate surface through controlled polishing conditions (abrasive grain size, load, oxidizing agents) and ion beam parameters (acceleration voltage, beam current, treatment time). These parameter changes optimize the surface state to reduce polycrystal generation rate while maintaining reasonable production efficiency
2Manufacturing precision
If chemical mechanical polishing is performed with optimized parameters, then surface quality is improved, but processing time and complexity increase
Solution Approach 1:
The patent segments the surface treatment process into distinct stages: chemical mechanical polishing with controlled parameters followed by gas cluster ion beam treatment. This segmentation allows each process to be optimized independently for surface quality while keeping the overall process manageable and not excessively complex
3Manufacturing precision
If ion beam treatment is applied to remove foreign substances and oxide films, then substrate purity is improved, but processing damage may occur
Solution Approach 1:
The patent carefully controls ion beam parameters including acceleration voltage (5-10 kV), beam current (5-10 nA), and treatment time to achieve effective removal of foreign substances and oxide films while minimizing processing damage. The parameter optimization balances substrate purity improvement with damage prevention
Solution Approach 2:
The gas cluster ion beam acts as an intermediary that gently removes contaminants and oxide films from the substrate surface through physical sputtering and chemical reactions, achieving substrate purification with minimal damage compared to more aggressive cleaning methods
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 effectively reduces the area ratio of polycrystal regions in the SiC epitaxial film to less than 10%, improving the substrate's quality and reducing processing damage, allowing for more accurate quantitative analysis and enhanced epitaxial film performance.
Implementation Method 1
A chemical mechanical polishing is performed on an SiC substrate
Implementation Method 2
a chemical mechanical polishing is performed on an SiC substrate. After performing the chemical mechanical polishing
Implementation Method 3
a beam of a cluster of noble gas ions is applied to a surface of the SiC substrate
Implementation Method 4
the ion beam treatment removes foreign substances and oxide films
Implementation Method 5
In an SiC crystal substrate according to the present disclosure, in an X-ray photoelectron spectrum under conditions of an incident X-ray energy of 250 eV and a photoelectron take-off angle of 45 degrees
Data Source
AI summary
In an X-ray photoelectron spectrum under conditions of incident X-ray energy of 250 eV and a photoelectron take-off angle of 45 degree, when a sum of an area of Si 2p1/2 spectrum and an area of Si 2p3/2 spectrum is 1, a sum of an area of a Si2+ spectrum, an area of a Si3+ spectrum, and an area of a Si4+ spectrum is smaller than 1.8.