SiC Substrate Mirror Surface Formation via Molten Alkali Etching
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Solution Overview
Problem
The high hardness and chemical stability of SiC substrates make them difficult to process, leading to long processing times and high costs due to the need for numerous steps to achieve a defect-free, mirror surface.
Innovation Solution
An etching method using molten sodium hydroxide at high temperatures with oxygen, where an oxide film is formed and removed at a higher rate on the Si surface than the C surface, allowing for defect-free, mirror surface formation without etch pits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional polishing and grinding methods are used on SiC substrates, then a defect-free surface can be obtained, but the processing time and cost increase significantly
Solution Approach 1:
The patent changes the etching parameters by using molten alkali at high temperatures (above melting point of alkali) instead of traditional polishing methods. This parameter change enables rapid removal of damaged layers and formation of mirror surfaces without the time-consuming multiple polishing steps, thereby reducing processing time while maintaining surface quality
Solution Approach 2:
The patent utilizes the phase transition of alkali from solid to molten state by heating above its melting point. This phase transition enables the alkali to effectively etch the SiC substrate and form oxide films at high temperatures, achieving defect-free mirror surfaces much faster than traditional mechanical polishing methods
2Manufacturing precision
If multiple processing steps are used to form a good surface on SiC substrate, then a defect-free state can be achieved, but the number of processing steps increases
Solution Approach 1:
The patent merges multiple traditional processing steps (polishing, grinding, and etching) into a single molten alkali etching process. By controlling the etching conditions to form oxide films and remove damaged layers simultaneously, the patent achieves defect-free mirror surfaces with fewer processing steps, thereby reducing process complexity
3Manufacturing precision
If precise polishing is performed on SiC substrate, then a defect-free surface can be obtained, but the processing cost increases
Solution Approach 1:
The patent replaces mechanical polishing systems with a chemical etching system using molten alkali. This substitution eliminates the need for expensive precision polishing equipment and multiple processing steps, significantly reducing manufacturing cost while achieving defect-free mirror surfaces through controlled oxide film formation and removal
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 efficient formation of a mirror surface over a wide range at a high rate, reducing processing time and cost by avoiding etch pits and anisotropic etching.
Implementation Method 1
forming an oxide film on etching target surfaces a SiC substrate, the surfaces of the SiC substrates including a Si surface and a C surface
Implementation Method 2
removing the Si surface of etching target surfaces at a higher rate than for the C surface while performing the step of forming the oxide film
Data Source
AI summary
An etching method in which: molten sodium hydroxide in a prescribed temperature range is used as a molten alkali, whereby an Si surface of an etching surface of an SiC substrate, in which the substrate surface is configured from the Si surface and a C surface, is removed at a higher speed than is the C surface while an oxide film is formed on the etching surface in a high-temperature environment containing oxygen.