Monocrystalline Silicon Growth CV Value Control
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Solution Overview
Problem
The existing methods for growing monocrystalline silicon using the Czochralski process face challenges in quickly setting pull-up conditions to inhibit abnormal growth without increasing the electrical resistivity, as calculating the temperature gradient requires actual measurement data and reducing pull-up speed can lead to higher resistivity.
Innovation Solution
The method uses the CV value, which is the product of dopant concentration and pull-up speed, as an index to determine growth conditions, allowing for quick calculation of critical points and resetting of pull-up conditions to prevent abnormal growth without increasing resistivity, by creating a target CV value profile that does not exceed the critical CV value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the temperature gradient G is calculated using actual measurement data of the solid-liquid interface shape, then the accuracy of determining critical pull-up conditions is improved, but the time required to examine improvement conditions increases
Solution Approach 1:
The patent creates a simplified copy model by using the CV value (product of dopant concentration and pull-up speed) as an alternative index that replicates the essential information needed to determine critical pull-up conditions without requiring complex temperature gradient calculations. This copying approach allows quick examination of improvement conditions while maintaining sufficient accuracy for practical purposes.
2Reliability
If the pull-up speed V is reduced to inhibit cell growth, then the occurrence of abnormal growth is suppressed, but the electrical resistivity of the monocrystalline silicon increases
Solution Approach 1:
The patent changes the approach from directly controlling pull-up speed to controlling the CV value (product of dopant concentration and pull-up speed). By adjusting the dopant concentration C, the system can maintain an appropriate CV value to suppress cell growth while allowing the pull-up speed V to remain high, thus preventing the increase in electrical resistivity that would result from excessive speed reduction.
3Reliability
If a critical pull-up speed is determined to inhibit dislocation, then the abnormal growth is prevented, but the productivity decreases due to excessively reduced pull-up speed
Solution Approach 1:
The patent establishes a preliminary criterion using the CV value that predicts the onset of cell growth before it occurs. By monitoring and controlling the CV value to remain below the critical threshold, the system can proactively adjust dopant concentration or pull-up speed to prevent abnormal growth, eliminating the need for excessive speed reductions and maintaining high productivity.
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 enables quick and effective setting of pull-up conditions to inhibit abnormal growth, maintaining low resistivity in monocrystalline silicon, with resistivity levels of 1.3 mΩ·cm or less for red phosphorus, 2.6 mΩ·cm or less for arsenic, and 20 mΩ·cm or less for antimony, without increasing electrical resistivity.
Implementation Method 1
a volatile dopant such as red phosphorus (P), arsenic (As) or antimony (Sb) is added to a silicon melt
Implementation Method 2
G denotes a temperature gradient (K/mm) of a melt under a solid-liquid interface
Data Source
AI summary
There is provided a growing method of monocrystalline silicon including: pulling up monocrystalline silicon from a dopant-added melt in which a dopant is added to a silicon melt and growing the monocrystalline silicon according to Czochralski process, in which the monocrystalline silicon is grown by calculating a critical CV value, which is a product of a dopant concentration C and a pull-up speed V at a point of time when an abnormal growth occurred in the monocrystalline silicon; and controlling at least one of the dopant concentration C or the pull-up speed V to make a CV value, which is a product of the dopant concentration C and the pull-up speed V at the point of time, below the critical CV value.