SiC Substrate Anodization for Flat Oxide Thickness Control
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Solution Overview
Problem
Existing methods for treating silicon carbide substrates, such as electrolytic etching, and the anodization, are not effective in the field of environmental pollution control and purification technology, specifically involving the removal of Hg0 from flue gas and Hg2+ from waste liquid, with existing technologies are not effective in existing technologies are not effective in existing technologies are not effective in existing technologies are not effective in existing technologies are not effective in forming a flat surface on silicon carbide single crystal substrates and controlling film thickness efficiently.
Innovation Solution
A method involving anodization of silicon carbide single crystal substrates using an electrolyte solution free of fluorine anions, followed by etching with specific etchants, allows for controlled film thickness and surface flatness on silicon carbide single crystal substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrolytic etching using hydrofluoric acid or etchants containing fluorine anions is used, then etching of silicon carbide substrate can be achieved, but sufficient etching is not obtained and flat surface formation is difficult
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte solution by excluding fluorine anions and using alternative electrolytes such as sulfuric acid, phosphoric acid, or boric acid. This parameter change enables both effective etching and flat surface formation on silicon carbide substrates, resolving the contradiction between etching effectiveness and surface flatness.
2Manufacturing precision
If thermal oxidation at 800 to 1200° C. for 1 to 5 hours is used, then oxidized film formation is achieved, but processing time is long and manufacturing efficiency is low
Solution Approach 1:
The patent replaces the thermal oxidation process (heating system) with an electrochemical anodization process (electrical system). By applying voltage to the silicon carbide substrate in an electrolyte solution, oxidized films are formed rapidly at room temperature or low temperatures, achieving both film uniformity and high processing speed without the need for long thermal treatment.
3Manufacturing precision
If conventional etching methods are used, then material removal is achieved, but controlling film thickness precisely is difficult
Solution Approach 1:
The patent implements feedback control by monitoring the relationship between applied voltage, current density, and treatment time during anodization. By controlling these parameters and their combinations, the film thickness can be precisely controlled according to the formula: film thickness ∝ (voltage × time) / current density. This provides accurate thickness control while maintaining relatively simple process conditions.
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
Enables the formation of an oxidized film on silicon carbide single crystal substrates with controlled thickness and smooth surfaces under mild conditions, improving processing accuracy and reducing manufacturing costs.
Implementation Method 1
a step (A) of forming an oxidized film on at least one main surface of the silicon carbide single crystal substrate by anodization using the silicon carbide single crystal substrate as an anode and applying a voltage while bringing the at least one main surface of the silicon carbide single crystal substrate into contact with an electrolyte solution free of a fluorine anion
Implementation Method 2
by anodization using the silicon carbide single crystal substrate as an anode and applying a voltage while bringing the at least one main surface of the silicon carbide single crystal substrate into contact with an electrolyte solution
Data Source
AI summary
A silicon carbide single crystal substrate processing method by which the thickening of a desired surface of a SiC single crystal substrate can be achieved in a short time under mild conditions such as room temperature; and a silicon carbide single crystal substrate processing system applicable to the processing method. The silicon carbide single crystal substrate processing method includes performing anodic oxidation, in which a voltage is applied using the silicon carbide single crystal substrate as an anode while at least one main surface of the silicon carbide single crystal substrate is brought into contact with an electrolyte solution that does not contain fluorine anions, to thereby form an oxide film on the main surface.