Arc Discharge Apparatus Electrode Geometry for Crucible Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
During the manufacturing of large-diameter fused silica crucibles, electrode oscillation occurs during arc discharge, leading to unstable arcs, deterioration of crucible properties, and potential electrode breakage, which affects the quality of the crucible and the single-crystal silicon pulled from it.
Innovation Solution
The method involves setting a specific ratio of the distance between the contact position of carbon electrodes to their diameter during arc discharge, within the range of 0 to 0.9, and maintaining a power density of 40 to 1,700 kVA/cm² to control electrode oscillation and ensure arc stability, using a high-output arc discharge apparatus with carbon electrodes arranged to prevent excessive oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the diameter of the fused silica crucible is increased to over 300 mm to meet demand for higher efficiency, then the productivity is improved, but electrode oscillation occurs during arc discharge leading to unstable arcs and deterioration of crucible properties
Solution Approach 1:
The invention changes the geometric parameters of the carbon electrodes by specifying that the distance between the contact position and the front end should be 0.05 to 0.2 times the electrode diameter. This parameter optimization prevents electrode oscillation during arc discharge, thereby maintaining arc stability even when manufacturing large-diameter crucibles with improved productivity
2Strength
If the diameter of the carbon electrode is increased to prevent oscillation, then the strength is improved, but power density is decreased and arc output becomes unstable
Solution Approach 1:
Instead of increasing electrode diameter, the invention optimizes the distance parameter from the contact position to the front end (setting it to 0.05 to 0.2 times the electrode diameter). This maintains appropriate power density while preventing oscillation, thus preserving both electrode strength and arc output stability
3Strength
If other materials than carbon are used for electrodes to increase strength, then the strength is improved, but crucible properties deteriorate due to composition release into melting atmosphere
Solution Approach 1:
The invention maintains carbon as the electrode material but optimizes the geometric parameter (distance from contact position to front end to be 0.05 to 0.2 times electrode diameter). This prevents oscillation-induced breakage and composition release, thereby preserving crucible properties while achieving sufficient electrode strength
4Strength
If the amplitude of electrode oscillation increases, then the electrode may break, but increasing oscillation amplitude also causes current change and further oscillation
Solution Approach 1:
The invention applies preliminary anti-action by pre-setting the electrode geometry (distance from contact position to front end as 0.05 to 0.2 times electrode diameter) to prevent oscillation before it can develop. This initial configuration counteracts the tendency toward oscillation, preventing both current instability and electrode breakage
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 approach stabilizes the arc discharge, prevents electrode oscillation, and enhances the quality of the fused silica crucible by maintaining the properties of the inner surface, bubble distribution, and reducing the risk of electrode breakage, thereby improving the semiconductor single-crystal properties.
Implementation Method 1
heating the vitreous silica-deposited layer by the arc discharge for vitrification
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
An arc discharge method of the present invention includes the steps of: heating and melting a non-conductive object by arc discharge using a plurality of carbon electrodes in an output range of 300 to 12,000 kVA; and setting a ratio of the distance between a contact position at which the carbon electrodes come in contact with each other and a front end to the diameter of the carbon electrode during the start of the arc discharge to be in the range of 0.001 to 0.9.