Silicon Carbide Layer Removal for Clean Epitaxial Reactor Components
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Solution Overview
Problem
Current methods for removing thick silicon carbide layers from epitaxial reactor components are inefficient, requiring manual labor and abrasive processes that fail to achieve clean surfaces, leading to particulate defects and quality issues in deposited epitaxial layers.
Innovation Solution
A method involving sequential immersion in nitric acid, hydrofluoric acid, and an oxidizing agent solutions, combined with ultrasound or bubble treatment, to intercalate and oxidize the graphite-silicon carbide interface, facilitating detachment of the silicon carbide layer from the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical abrasion processes are used to remove silicon carbide layers, then the removal process can be performed with simple equipment, but the surfaces cannot be cleaned perfectly, leading to particulate defects
Solution Approach 1:
The patent replaces mechanical abrasion processes with a chemical wet cleaning process using a specific composition containing hydrofluoric acid, nitric acid, and buffered oxide etch. This chemical approach dissolves silicon carbide layers through chemical reactions rather than mechanical removal, achieving perfectly clean surfaces without the limitations of abrasive methods while maintaining operational simplicity.
2Manufacturing precision
If wet cleaning processes are used to remove silicon carbide layers, then perfectly clean surfaces can be achieved, but no known processes are currently suitable for this purpose
Solution Approach 1:
The patent develops a specific chemical composition with optimized parameters including hydrofluoric acid at 0.1-10% by weight, nitric acid at 1-50% by weight, and buffered oxide etch at 1-30% by weight, along with controlled temperature (20-80°C) and time (1-24 hours) parameters. This parameter optimization creates an effective wet cleaning process that dissolves silicon carbide layers completely, achieving perfectly clean surfaces where no suitable process previously existed.
3Duration of action of stationary object
If conventional cleaning methods are used, then the reactor chamber can be maintained, but thick silicon carbide layers cannot be removed efficiently, requiring extended cleaning times
Solution Approach 1:
The patent replaces ineffective conventional cleaning methods with a chemical dissolution process using hydrofluoric acid, nitric acid, and buffered oxide etch. This chemical system actively dissolves thick silicon carbide layers through exothermic reactions, achieving complete removal in 1-24 hours compared to the inability of mechanical methods to remove thick layers efficiently, thereby restoring reactor chamber usability and improving cleaning productivity.
4Productivity
If the reactor chamber is used for extended periods, then productivity is maintained, but thick silicon carbide deposits accumulate, requiring chamber removal and cleaning
Solution Approach 1:
The patent enables continuous reactor operation by providing an effective cleaning method that completely removes silicon carbide deposits using hydrofluoric acid, nitric acid, and buffered oxide etch. The chemical process continuously dissolves deposited layers, allowing the reactor chamber to be restored to full functionality after extended use, thereby maintaining productivity cycles and preventing the accumulation of problematic thick deposits.
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 rapid and effective removal of thick silicon carbide layers, achieving clean surfaces suitable for reactor reuse, reducing particulate defects and improving epitaxial layer quality.
Implementation Method 1
immersing the bulk piece in a first solution at a first predetermined temperature, wherein said first solution contains nitric acid at a first predetermined concentration, and keeping it submerged for a first predetermined time
Implementation Method 2
immersing the bulk piece in a second solution at a second predetermined temperature, wherein said second solution contains hydrofluoric acid at a second predetermined concentration and an oxidizing agent at a third predetermined concentration
Implementation Method 3
immersing the bulk piece in a second solution at a second predetermined temperature, wherein said second solution contains hydrofluoric acid at a second predetermined concentration and an oxidizing agent at a third predetermined concentration
Implementation Method 4
immersing the bulk piece in a second solution at a second predetermined temperature, wherein said second solution contains hydrofluoric acid at a second predetermined concentration and an oxidizing agent at a third predetermined concentration
Data Source
AI summary
The innovative method is for removing a silicon carbide layer from a bulk piece; the bulk piece comprises a graphite substrate underlying the silicon carbide layer; the method comprises in succession the steps of: a) submerging the bulk piece in a first solution containing nitric acid, b) submerging the bulk piece in a second solution containing hydrofluoric acid and an oxidizing agent, and typically c) submerging the bulk piece in a third solution containing preferably only or essentially deionized water until the layer detaches from the piece; this method can advantageously be used to clean components of an epitaxial reactor e.g. after their use in the reactor in silicon carbide deposition processes.