SiC Substrate Surface Treatment via Si Vapor Etching
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Solution Overview
Problem
Conventional methods for removing latent scratches from SiC substrates are either too time-consuming or result in excessive substrate removal, degrading the quality of semiconductor materials during epitaxial growth and heat treatment.
Innovation Solution
A surface treatment method involving heating and etching the SiC substrate under Si atmosphere with controlled inert gas pressure between 0.01 Pa and 1 Pa, at temperatures between 1800°C and 2000°C, to quickly and effectively remove latent scratches, thereby preventing surface roughening and substrate over-removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional hydrogen etching is used to remove latent scratches, then the treatment can be performed, but it takes a lot of time because the etching rate is only several tens of nm/h to several hundreds of nm/h
Solution Approach 1:
The patent changes the etching parameters by using Si vapor pressure environment and high temperature (heating the storage container while storing the SiC substrate under Si vapor pressure) to dramatically increase the etching rate from several tens of nm/h to much higher rates, thereby reducing treatment time while maintaining effective removal of latent scratches
Solution Approach 2:
The patent utilizes the phase transition of Si material under vapor pressure conditions, where Si vapor deposits and reacts with the SiC substrate surface at elevated temperatures, enabling rapid etching and planarization of the substrate surface to remove latent scratches efficiently
2Manufacturing precision
If mechanical polishing is used to remove latent scratches, then the surface can be planarized, but it takes a lot of time because the polishing rate is 1 μm/h or less
Solution Approach 1:
The patent replaces the mechanical polishing system with a thermal-chemical etching system using Si vapor pressure and high temperature heating, which achieves surface planarization and latent scratch removal much faster than mechanical methods without the time consumption of conventional polishing processes
3Productivity
If high-vacuum Si atmosphere etching is used, then the etching rate is high, but too much substrate is removed
Solution Approach 1:
The patent employs feedback control by monitoring and adjusting the Si vapor pressure and heating conditions during the etching process to achieve the desired etching rate while controlling the amount of substrate removal, preventing excessive material loss while maintaining high productivity
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 method significantly shortens treatment time, adjusts etching rates to prevent excessive substrate removal, and ensures high-quality SiC substrates for semiconductor manufacturing by uniformly removing latent scratches without altering conventional processing efforts.
Implementation Method 1
a storage container is heated while the SiC substrate is stored within the storage container under Si vapor pressure. This results in etching the SiC substrate stored within the storage container
Implementation Method 2
heating, in a high vacuum environment, a SiC substrate having a damaged layer generated during polishing to form a carbonized layer on the substrate
Implementation Method 3
heating the SiC substrate having the carbonized layer under Si atmosphere to form an amorphous SiC layer on the SiC substrate
Implementation Method 4
removing the amorphous SiC layer on the SiC substrate by thermal etching
Implementation Method 5
thermally oxidizing the carbon layer on the SiC substrate to form an oxide film on the SiC substrate
Implementation Method 6
heating, under the presence of a polycrystalline SiC body, SiC powder and Ta plates in a nitrogen atmosphere, a SiC substrate cut out from a single crystal
Data Source
Figure 1
Figure 2(a)~2(f)
Figure 3
AI summary
When a SiC substrate (40) after performing mechanical treatment is heat-treated under SiC atmosphere to etch the SiC substrate (40), the etching rate is controlled by adjusting the inert gas pressure around the periphery of the SiC substrate (40). As a result, when latent scratches or the like exist in the SiC substrate (40), the latent scratches or the like can be removed. Accordingly, the surface of the SiC substrate (40) does not become rough, even if epitaxial growth and heat treatment and the like are performed. This can manufacture high-quality SiC substrates.