SiC Substrate Etching via Oxide Film Cycling
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Solution Overview
Problem
The challenge is to efficiently form a defect-free, mirror surface on silicon carbide (SiC) substrates, which are hard to process due to their high hardness and chemical stability, requiring numerous processing steps and time, especially during etching processes.
Innovation Solution
An etching method involving continuous isotropic etching with molten alkali at high temperatures and in an oxygen-rich environment, where an oxide film is formed and then removed, ensuring the oxidation rate exceeds the dissolution rate of the oxide film, allowing for defect-free and mirror surface formation without etch pits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional immersion etching with molten alkali is used, then etching can be performed on SiC substrate, but etch pits are formed and surface quality deteriorates
Solution Approach 1:
An oxide film is formed on the SiC substrate surface before the etching process. This preliminary oxidation creates a protective layer that prevents direct attack by the molten alkali, thereby avoiding etch pit formation while allowing controlled isotropic etching to proceed
Solution Approach 2:
The oxide film acts as an intermediary layer between the SiC substrate and the molten alkali. This intermediate layer modifies the interaction between the substrate and etchant, enabling defect-free etching by preventing direct contact between the aggressive molten alkali and the SiC surface
2Manufacturing precision
If precise polishing is performed to obtain defect-free surface, then surface quality improves, but the number of processing steps increases and productivity decreases
Solution Approach 1:
The mechanical polishing process is replaced with a chemical etching process using molten alkali. This substitution eliminates the need for multiple mechanical polishing steps while achieving defect-free mirror surfaces, thereby significantly reducing processing time and improving productivity
3Manufacturing precision
If SiC substrate is ground and polished to high precision, then surface quality improves, but processing time increases due to high hardness
Solution Approach 1:
Time-consuming mechanical grinding and polishing operations are replaced with a chemical etching process using molten alkali. The chemical process efficiently removes material and creates mirror surfaces without being hindered by the high hardness of SiC, thereby dramatically reducing processing time
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 enables the rapid formation of a mirror surface over a wide range, reducing processing time and costs by avoiding etch pits and effectively handling the hardness of SiC substrates, which is not achievable through traditional immersion etching methods.
Implementation Method 1
forming an oxide film on an etching target surface of a substrate... under an environment of high temperature and containing oxygen
Implementation Method 2
removing the oxide film by performing isotropic etching for the etching target surface... dissolution rate of the oxide film
Data Source
AI summary
An etching method for etching a substrate using a molten alkali, wherein, while an oxide coating is formed on the surface of the substrate PL to be etched in a high-temperature oxygen-containing environment, the surface to be etched is isotropically etched to remove the oxide coating using a molten alkali AL brought into a prescribed high-temperature range.