Silicon Melt Temperature Control Using Dual Pyrometers and PID
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Solution Overview
Problem
Existing temperature control systems for single crystal ingot growth struggle with accurately measuring and quickly controlling the temperature of a silicon melt due to natural convection, limited sensor placement, and noise in temperature readings, leading to inconsistent and slow convergence to target temperatures.
Innovation Solution
A temperature control device with dual temperature sensors positioned on both sides of the crucible chamber, performing noise-elimination filtering and arithmetic averaging, and a PID control system to accurately measure and control the silicon melt's temperature, ensuring precise temperature control during the ingot growth process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If one pyrometer is installed at the upper end of the chamber to measure temperature, then the device complexity is reduced, but the measurement precision is insufficient because it can only measure temperature at one position and the readings are affected by natural convection
Solution Approach 1:
The temperature measurement function is segmented into multiple independent pyrometers positioned at different locations (upper end, side surfaces) of the chamber. Each pyrometer measures temperature at its specific position, and the control unit integrates these multiple measurements to determine the overall melt temperature, thereby improving measurement precision while distributing device complexity across multiple simple components
Solution Approach 2:
The measurement approach transitions from a single-point measurement (one pyrometer at upper end) to multi-dimensional measurement by placing pyrometers at various positions including upper end and side surfaces. This spatial distribution across different dimensions allows comprehensive temperature monitoring that compensates for natural convection effects and improves overall measurement accuracy
2Productivity
If P control is used to adjust heater operation based on temperature deviation, then the ease of operation is maintained, but the productivity is reduced because it takes much time to converge the temperature to the target temperature
Solution Approach 1:
The system implements continuous feedback by constantly monitoring temperature at multiple positions with multiple pyrometers and using this real-time data to dynamically adjust heater power. The control unit processes feedback from all sensor positions and modifies heating intensity accordingly, enabling rapid temperature convergence while maintaining operational simplicity through automated closed-loop control
Solution Approach 2:
The control system transitions from static P control to dynamic control that adapts to real-time temperature conditions. By continuously adjusting heater power based on instantaneous temperature readings from multiple positions, the system optimizes the heating rate dynamically, achieving faster convergence to target temperature while maintaining ease of operation through automated adaptation
3Stability of the object's composition
If the crucible is rotated to achieve uniform temperature distribution, then the homogeneity of temperature is improved, but the measurement precision deteriorates because the pyrometer measures different positions at different times and noise data increases
Solution Approach 1:
The temperature monitoring is segmented into multiple fixed-position pyrometers that simultaneously measure temperature at different locations around the crucible. This segmentation allows the system to capture the temperature distribution pattern during rotation without the measurement inconsistency that occurs with a single moving measurement point, as each pyrometer continuously monitors its specific position while the crucible rotates
Solution Approach 2:
The system merges multiple temperature measurements from different positions and time points into a single comprehensive temperature assessment. The control unit integrates data from all pyrometers, combining their readings to determine the overall melt temperature and uniformity, thereby maintaining measurement precision while benefiting from the temperature homogenization effect of crucible rotation
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 solution allows for accurate and rapid temperature control of the silicon melt, reducing the time to converge to the target temperature by approximately 200 minutes compared to traditional methods, enhancing the quality and consistency of single crystal ingot production.
Implementation Method 1
one pyrometer 2 is installed at an upper end of a chamber 1, and one point of a surface of a silicon melt which is naturally convected into a crucible 3 by the pyrometer 2, is measured
Implementation Method 2
a heater 4... operation of a heater 4 is controlled
Data Source
AI summary
The present invention relates to a temperature control device for growing a single crystal ingot capable of accurately measuring a temperature of a silicon melt and quickly controlling to a target temperature during an ingot growing process, and a temperature control method applied thereto.The present invention provides a temperature control device for growing a single crystal ingot, which controls an operation of a heater for heating a crucible configured to accommodate a silicon melt, the device including: an input unit configured to measure a temperature of the silicon melt accommodated in the crucible and process the measured temperature of the silicon melt; a control unit configured to perform a proportional-integral-derivative (PID) calculation of one of the measured temperature T1 and the processing temperature T2 of the input unit and a set target temperature T0 and calculate as an output of the heater; and an output unit configured to input the output of the heater calculated in the control unit to the heater.