Seed Rotation Control for Single Crystal Ingot Eccentricity
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Solution Overview
Problem
The existing methods for growing single crystal ingots using the Czochralski method face challenges with resonance phenomena in the silicon melt, leading to fluctuations and eccentric growth, which result in uneven ingot diameters and difficulties in maintaining consistent oxygen concentration and defect-free regions, particularly due to constant seed rotation numbers that can cause zigzag growth and increased processing time.
Innovation Solution
A pulling control device and method that dynamically adjusts the seed rotation number in real time by varying the target seed output rotation number based on input values, using either a sine or linear function to match the rotation form for each ingot length, preventing resonance and eccentricity by controlling the seed cable's rotation number.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant seed rotation number is used during single crystal ingot growth, then the oxygen concentration and defect-free region can be controlled, but resonance phenomena occur in the silicon melt causing fluctuation and eccentric growth
Solution Approach 1:
The patent applies dynamics by transitioning from a constant seed rotation number to a dynamically variable rotation number that changes over time during the crystal growth process. The rotation number is adjusted according to a predetermined function to avoid resonance frequencies that cause melt fluctuation and eccentric growth, while still maintaining control over oxygen concentration and defect-free regions.
Solution Approach 2:
The patent implements parameter changes by modifying the seed rotation number parameter throughout the growth process. Instead of keeping the rotation number constant, the system varies it according to a predetermined function to prevent resonance phenomena in the silicon melt, thereby improving ingot diameter uniformity while preserving oxygen concentration control.
2Manufacturing precision
If the seed rotation number is set to a specific value to control oxygen concentration, then radial oxygen distribution is optimized, but resonance phenomenon occurs causing liquid surface fluctuation and eccentricity
Solution Approach 1:
The patent applies periodic action by using a predetermined function to vary the seed rotation number in a systematic manner over time. This periodic variation ensures that the rotation number does not remain at specific values that would cause resonance, thereby maintaining melt stability while still achieving controlled radial oxygen concentration distribution through the structured rotation pattern.
Solution Approach 2:
The system transitions from a static rotation number setting to a dynamic one where the rotation number continuously adjusts according to a predetermined function. This dynamic adjustment prevents the melt from entering resonant states that cause surface fluctuation and eccentricity, while maintaining effective control over radial oxygen concentration.
3Ease of operation
If a constant seed rotation number is used, then the growth process is simple to control, but eccentricity phenomenon occurs requiring additional grinding processes and increasing processing time
Solution Approach 1:
The patent applies preliminary action by pre-defining a rotation number variation function that prevents eccentricity from occurring during the growth process. By planning and implementing the rotation number changes in advance according to a predetermined function, the system avoids the need for subsequent grinding processes to correct eccentricity, thereby reducing total processing time while maintaining operational simplicity.
Solution Approach 2:
The patent implements skipping by eliminating the need for additional grinding processes through proactive rotation number control. By varying the rotation number according to a predetermined function during growth, the system prevents eccentricity formation, allowing the process to skip the time-consuming grinding step and proceed directly to completion.
4Manufacturing precision
If the seed rotation number varies dynamically, then resonance and eccentricity are prevented, but the control system becomes more complex
Solution Approach 1:
The patent applies self-service by implementing a predetermined function-based control system that automatically adjusts the seed rotation number without requiring complex real-time monitoring or intervention. The system uses pre-programmed rotation patterns that inherently prevent resonance and eccentricity, simplifying the control architecture while achieving high ingot straightness through autonomous operation.
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 allows for uniform ingot growth, reducing processing time and ensuring consistent oxygen concentration and defect-free regions by preventing resonance and eccentricity, enabling straightforward diameter formation and improved quality control.
Implementation Method 1
it has been found that the cause of fluctuation of the silicon melt is due to resonance. In addition, a resonance phenomenon of a melt becomes larger as a single crystal melt decreases, and a liquid surface wave tends to occur markedly when it is close to an integral multiple of rotation number of a seed.
Data Source
AI summary
The present invention relates to a pulling control device for growing a single crystal ingot capable of controlling an eccentricity of a single crystal ingot by varying a seed rotation number in real time, and a pulling control method applied thereto.According to the present invention, a pulling control device for growing a single crystal ingot and a pulling control method applied thereto may minimize that a seed rotation number (f) is set to a specific rotation number (fo) causing a resonance phenomenon of a melt by providing a target seed output rotation number (T_fout) that varies in real time so as to match a rotation form for each length of an ingot according to inputting a target seed input rotation number (T_fin) and controlling a rotation number (f) of a seed cable, and it is possible to prevent fluctuation of the melt and an eccentricity phenomenon of the ingot.