Czochralski Ingot Diameter Control via Load Feedback
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Solution Overview
Problem
The Czochralski method for growing silicon single crystal ingots results in diameter deviations due to seed shaking during initial growth, reducing the usable area of the ingot.
Innovation Solution
A diameter controlling system that includes a seed chuck, a load measuring part, a load adjusting part with a linear motion guide, and a controlling part to adjust the load applied to the ingot, ensuring the seed is not shaken by applying a target load similar to that of the ingot's second half growth, where diameter deviations are minimized.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the seed is pulled up at a predetermined speed during initial growth, then the ingot growth process can be maintained, but the seed portion shakes causing diameter deviation
Solution Approach 1:
The patent applies preliminary anti-action by applying a counterbalancing force through the load adjusting part before the seed chuck can shake during initial growth. The controlling part activates the load adjusting part to apply an opposing force that counteracts the shaking caused by rapid pulling, thereby preventing diameter deviation while maintaining growth speed.
Solution Approach 2:
The patent implements feedback control where the controlling part continuously monitors the load applied to the seed chuck through the load measuring part and adjusts the load adjusting part accordingly. This closed-loop feedback mechanism ensures that the seed chuck maintains stable loading conditions throughout the growth process, preventing shaking and ensuring uniform ingot diameter.
2Productivity
If the pulling speed is increased to improve productivity, then the growth rate increases, but the seed shaking causes diameter deviation and reduces usable area
Solution Approach 1:
The load adjusting part applies a counterbalancing force in advance to counteract the shaking effects of high-speed pulling. By preliminarily applying this opposing force through the controlling part, the system maintains diameter uniformity even at increased growth rates, converting what would be a harmful shaking effect into a controlled balancing act.
Solution Approach 2:
The patent changes the load parameter dynamically during the growth process. The controlling part adjusts the load applied to the seed chuck based on real-time measurements, modifying this critical parameter to compensate for shaking effects at high pulling speeds, thereby maintaining diameter uniformity while achieving high productivity.
3Device complexity
If the load on the seed chuck is not adjusted, then the system remains simple, but the light weight of initial ingot causes shaking and diameter deviation
Solution Approach 1:
The system achieves self-service through automatic feedback control. The load measuring part continuously monitors the actual load, and the controlling part automatically adjusts the load adjusting part without requiring external intervention. This self-regulating mechanism maintains diameter uniformity while adding minimal complexity to the overall system.
Solution Approach 2:
The feedback loop consisting of the load measuring part and controlling part provides automatic adjustment of the load on the seed chuck. This feedback mechanism compensates for the light weight of initial ingots by dynamically adjusting the applied load, preventing shaking and ensuring diameter uniformity with only moderate increases in system complexity.
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
The system effectively reduces diameter deviations and prevents seed shaking during initial growth, ensuring uniform ingot growth and reducing the risk of uneven growth and seed falling due to rapid pulling speed.
Implementation Method 1
a lead screw (14) having a threaded surface, and a support unit (15) capable of linear motion in the lead screw (14)
Implementation Method 2
a motor (17) connected to the upper end of the lead screw (14)
Implementation Method 3
a cable connected to an upper surface of the seed chuck (12)
Data Source
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AI summary
The embodiments of the present invention provides a diameter controlling system of the single crystal ingot for controlling a diameter deviation of a silicon ingot during the growth of silicon ingot by a Czochralski method, it may include a seed chuck for supporting a silicon ingot combined with a seed crystal and grown; a measuring part connected to an upper surface of the seed chuck with a cable and configured to measure a load applied to the seed chuck; a load adjusting part for moving a position of the seed chuck vertically while the seed chuck is connected to the cable to change a load applied to the silicon ingot; and a controlling part for controlling the load applied to the silicon ingot by driving the load adjusting part according to the load value measured from the measuring part. Therefore, shaking of the seed during the growth process of the single crystal ingot is prevented, and thus the diameter deviation of the growing single crystal ingot may be reduced.