Single Crystal Furnace Crucible Position Control via Conical Valve Weight Feedback
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Solution Overview
Problem
The existing methods for producing silicon single crystals, such as the Czochralski method, face challenges in accurately controlling the crucible position during the recharge process, leading to variations in melting time and potential quartz crucible deformation or breakage due to uneven heating and raw material distribution.
Innovation Solution
A method that involves using a recharge pipe with a conical valve to precisely set and maintain the distance between the crucible and the purge tube by measuring weight changes and detecting contact to ensure consistent raw material positioning, utilizing a load cell and potentially a CCD camera for automated control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the crucible position is not accurately controlled during recharge, then the raw material distribution becomes uneven, but this leads to variations in melting time and potential quartz crucible deformation or breakage
Solution Approach 1:
The patent employs a load cell to detect weight changes of the conical valve during the recharge process. When the valve contacts the raw material surface, the weight change provides feedback signal to automatically stop the charging process, ensuring precise crucible position control and preventing uneven raw material distribution that could lead to melting variations and crucible damage
Solution Approach 2:
The patent replaces manual positioning methods with an automated detection system using a load cell to sense weight changes. This mechanical-to-electrical substitution enables precise, real-time monitoring of the charging process, eliminating human error in position control and preventing crucible deformation or breakage
2Quantity of substance
If multiple recharge operations are performed to add sufficient raw material, then the raw material amount is adequate, but this increases production time and operational complexity
Solution Approach 1:
The patent performs preliminary calculation of the required raw material quantity based on the single crystal growth amount before the recharge operation. The conical valve is pre-positioned and the charging process is controlled in one operation to add the exact needed amount, eliminating the need for multiple recharge cycles and improving production efficiency
Solution Approach 2:
The system uses the load cell to automatically detect when the raw material surface is reached during charging. This self-detecting mechanism ensures the precise addition of the calculated raw material amount in a single operation, preventing both undercharging (requiring additional recharge) and overcharging (wasting time and material)
3Ease of operation
If the conical valve is moved downward to open the recharge pipe, then the raw material is input to the crucible, but this may cause improper positioning if not precisely controlled
Solution Approach 1:
The load cell provides real-time weight feedback during the conical valve downward movement. When the valve contacts the raw material surface, the weight change signals the control system to stop the movement, ensuring precise positioning without requiring complex manual operation or estimation
Solution Approach 2:
The patent replaces manual positioning judgment with automated weight-based detection. The load cell converts the mechanical contact between the valve and raw material into an electrical signal, enabling precise control of the charging process and eliminating the imprecision of manual 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 precise control of the crucible position, reducing variations in melting time and preventing issues like quartz crucible deformation or breakage, thereby enhancing the efficiency and reliability of the single crystal production process.
Implementation Method 1
measuring weight changes and detecting contact
Implementation Method 2
a heater that heats the raw material melt is placed in a main chamber
Implementation Method 3
the raw material is melted by heating by the heater
Implementation Method 4
The grown single crystal is housed in a pull chamber connected to a main chamber upper part via a gate valve and is cooled
Data Source
AI summary
The present invention is a method for producing a single crystal, the method in which, after a charging process, a crucible position setting process including a step of placing a lower end of a conical valve below a lower end of a purge tube, a step of performing a movement in such a way that the conical valve and the crucible get relatively closer to each other while measuring changes in the weight of the conical valve, a step of detecting contact between the lower end of the conical valve and an upper end of a raw material based on the rate of change in the weight of the conical valve, a step of measuring the position of the upper end of the raw material based on the position of the lower end of the conical valve at which the contact was detected, and a step of setting the position of the crucible so that the spacing between the lower end of the purge tube and the upper end of the raw material charged in the crucible becomes a predetermined distance and a melting process including a crucible position adjusting step of adjusting the position of the crucible so that the spacing between the lower end of the purge tube and the upper end of the raw material maintains a predetermined distance in accordance with the progress of melting of the raw material are performed. As a result, it is possible to perform control so that the spacing between the lower end of the purge tube and the upper end of the raw material charged in the crucible becomes a predetermined distance.