Monocrystalline Silicon Resistivity Control via Dopant Gradient
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Typical methods for producing monocrystalline silicon with low resistivity often result in dislocations during the Czochralski process, leading to increased production costs due to the need for repeated seed crystal immersion and adjustments in dopant concentration, which can cause abnormal growth and freezing point depression.
Innovation Solution
Controlling the resistivity at the straight-body start point to be higher than the target value and then sequentially reducing it to prevent dislocations, using a Czochralski process with silicon melts doped with red phosphorus or arsenic, maintaining a straight-body diameter between 301 mm to 330 mm without increasing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the dopant concentration is increased to reduce the resistivity of monocrystalline silicon, then the electric resistivity is reduced, but abnormal growth due to compositional supercooling occurs and dislocations are generated
Solution Approach 1:
The patent applies preliminary action by carefully controlling the dopant concentration at the beginning of the pulling process to be within a specific range (1.0×10^19 to 5.0×10^19 atoms/cm³). This preliminary control prevents compositional supercooling and dislocation formation before they can occur, allowing the entire straight body portion to achieve low resistivity without quality defects.
Solution Approach 2:
The patent changes the parameter of dopant concentration to an optimized range (1.0×10^19 to 5.0×10^19 atoms/cm³) that balances two competing requirements: low enough to prevent compositional supercooling and dislocation formation, yet high enough to achieve the desired low resistivity (0.5-2.0 mΩcm) in the final product.
2Manufacturing precision
If the dopant concentration is increased to achieve low resistivity throughout the monocrystalline silicon, then the resistivity is reduced, but freezing point depression becomes very large causing abnormal growth
Solution Approach 1:
The patent changes the dopant concentration parameter to a specific range (1.0×10^19 to 5.0×10^19 atoms/cm³) that prevents excessive freezing point depression. This parameter optimization ensures stable crystal growth by keeping the compositional supercooling within acceptable limits while still achieving the target resistivity.
3Use of energy by moving object
If the resistivity is reduced to meet target values, then the power consumption is decreased, but dislocations occur during the pulling process requiring repeated seed crystal immersion
Solution Approach 1:
The patent applies preliminary action by setting the dopant concentration within the optimal range (1.0×10^19 to 5.0×10^19 atoms/cm³) before the pulling process begins. This preliminary optimization prevents dislocation formation during growth, eliminating the need for repeated seed crystal immersion and re-pulling operations, thereby maintaining high production efficiency while achieving low power consumption.
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 prevents dislocation occurrence, allowing for the production of monocrystalline silicon with low resistivity without repeating the pulling process, thus maintaining production efficiency and reducing costs.
Implementation Method 1
growing the monocrystalline silicon having a straight-body diameter in a range from 301 mm to 330 mm that is pulled up through a Czochralski process from a silicon melt including a dopant in a form of red phosphorus
Implementation Method 2
when the concentration of the dopant to be added to a silicon melt is increased in order to reduce the resistivity of the monocrystalline silicon to be pulled up, a freezing point depression of the silicon melt becomes very large
Data Source
AI summary
A production method of monocrystalline silicon includes: growing the monocrystalline silicon having a straight-body diameter in a range from 301 mm to 330 mm that is pulled up through a Czochralski process from a silicon melt including a dopant in a form of arsenic; controlling a resistivity of the monocrystalline silicon at the straight-body start point to fall within a range from 2.50 mΩcm to 2.90 mΩcm; and subsequently sequentially decreasing the resistivity of the monocrystalline silicon to fall within a range from 1.6 mΩcm to 2.0 mΩcm at a part of the monocrystalline silicon.