Semiconductor Crystal Remelting Detection via Weight and Electrical Signals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for remelting silicon single crystals require visual confirmation to determine if the crystal is fully molten, leading to operator burden, wasteful energy consumption, and risk of crucible damage due to incomplete melting and prolonged processing times.
Innovation Solution
A semiconductor single crystal pulling apparatus equipped with a remelting detection apparatus that uses weight changes to detect completion of melting and a lowermost end detection apparatus that electrically detects the crystal's position, allowing for automated remelting without visual confirmation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If visual confirmation by operator is used to determine melting completion, then the crystal can be monitored, but operator burden increases and the process becomes inefficient
Solution Approach 1:
The patent replaces the manual visual confirmation method with an automated optical detection system. A detector automatically monitors whether the crystal has fully melted by detecting the presence or absence of the crystal in the melt, eliminating the need for operator visual inspection and significantly reducing operational burden while maintaining reliable detection.
Solution Approach 2:
The detection system enables the remelting process to monitor and determine its own completion status automatically. The detector continuously observes the crystal melting state and autonomously determines when melting is complete, allowing the system to self-regulate without external operator intervention.
2Productivity
If the crystal is left in the melt after melting completion, then no additional action is needed, but electric power is wastefully consumed and melt temperature increases causing crucible degradation
Solution Approach 1:
The patent implements a feedback control system where the detector continuously monitors the crystal melting state and provides real-time information to the control mechanism. When the detector determines that melting is complete, it automatically triggers the wire to pull the crystal out of the melt, creating a closed-loop system that prevents energy waste by immediately stopping the heating process at the optimal moment.
Solution Approach 2:
The system employs periodic detection and automated periodic action to determine melting completion. The detector periodically checks the crystal state, and upon detecting completion, immediately initiates the crystal removal action, ensuring energy is not wasted during extended periods after melting completion.
3Productivity
If the crystal immersion depth is increased to ensure complete melting, then melting efficiency improves, but the risk of crystal contact with crucible bottom increases
Solution Approach 1:
The patent employs dynamic control of the wire position and crystal immersion depth throughout the remelting process. The system adjusts the immersion depth dynamically based on real-time detection of the crystal melting state, allowing optimal melting efficiency while automatically preventing excessive immersion that would cause crucible contact. The wire can be automatically pulled up when the crystal approaches the crucible bottom.
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
Enables efficient and accurate remelting by automating the process, reducing operator burden, minimizing energy waste, and preventing crucible damage by detecting completion of melting through weight changes and electrical detection of the crystal's position.
Implementation Method 1
a remelting detection apparatus which detects that remelting of a lower end portion of the semiconductor single crystal is completed from a change in weight of the semiconductor single crystal
Implementation Method 2
a lowermost end detection apparatus which detects a lowermost end of the semiconductor single crystal from a position where no current flows between the semiconductor single crystal and the melt
Implementation Method 3
a heater for performing heating and thermal insulation to a crucible containing a melt
Implementation Method 4
the lower end portion of the semiconductor single crystal is immersed in the melt so as to be remolten
Data Source
AI summary
A single crystal pulling apparatus including: a remelting detection apparatus which detects that remelting of a lower end portion of the semiconductor single crystal is completed from a change in weight of the semiconductor single crystal when the lower end portion of the semiconductor single crystal is immersed in the melt to be remolten by using the wire; and a lowermost end detection apparatus which detects a lowermost end of the semiconductor single crystal from a position where no current flows between the semiconductor single crystal and the melt when the semiconductor single crystal is taken up with the use of the wire while applying a voltage between the semiconductor single crystal and the melt by applying a voltage between the crucible and the wire.