Silicon Single Crystal Growth via Radial Magnetic Field Gradient Control
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Solution Overview
Problem
The Czochralski method for manufacturing silicon single crystals faces challenges in maintaining a stable temperature gradient near the crystal solid-liquid interface, leading to fluctuations that result in unwanted defect regions and reduced productivity, especially when pulling large-diameter crystals with rapid cooling structures.
Innovation Solution
Applying a horizontal magnetic field with a radial magnetic field intensity gradient of 5.5 to 10 Gauss/mm and controlling the pulling rate to crystal temperature gradient ratio to minimize temperature fluctuations, ensuring a stable crystal growth and desired defect region formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a rapid cooling structure is used to pull large-diameter silicon single crystals, then productivity is improved, but temperature gradient fluctuation increases causing defect regions
Solution Approach 1:
A magnetic field is introduced as an intermediary to control melt convection. The magnetic field acts as a mediator between the heating system and the crystal growth interface, suppressing turbulent convection and stabilizing temperature distribution without directly interfering with the rapid cooling process or crystal pulling speed
Solution Approach 2:
The invention changes the magnetic field parameters (strength, distribution, orientation) to optimize melt convection control. By adjusting magnetic field parameters, the system maintains stable temperature gradient while enabling high productivity crystal pulling
2Manufacturing precision
If magnetic field strength is increased to suppress melt convection, then temperature stability improves, but device complexity increases
Solution Approach 1:
The magnetic field system is segmented into multiple independent coils or magnet assemblies. This segmentation allows distributed control of magnetic field strength and distribution, reducing the complexity of controlling a single large magnetic field while achieving the same convection suppression effect
Solution Approach 2:
The magnetic field system is designed with dynamic adjustment capabilities, allowing real-time modification of field strength and distribution. This dynamic control enables optimization of temperature stability while managing device complexity through adaptive rather than static configurations
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 effectively suppresses melt convection, stabilizes the crystal temperature gradient, and reduces diameter fluctuations, enabling high-quality single crystal production with desired defect regions and improved productivity and yield, even for large-diameter crystals.
Implementation Method 1
a horizontal magnetic field is applied to a melt, a convection of the melt is suppressed
Implementation Method 2
Applying a horizontal magnetic field with a radial magnetic field intensity gradient of 5.5 to 10 Gauss/mm
Data Source
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AI summary
In a method of manufacturing a single crystal based on a Czochralski method of applying a horizontal magnetic field, the present invention provides a method of manufacturing a single crystal, wherein the single crystal is pulled in such a manner that a radial magnetic field intensity gradient ΔBr/ΔRc in a direction connecting central points of magnetic field generation coils exceeds 5.5 (Gauss/mm) and becomes 10 (Gauss/mm) or below where an origin O is a central part of the single crystal on a solid-liquid interface, ΔBr (Gauss) is a variation in a magnetic field intensity from the origin O to a crucible inner wall on a surface of a melt, and ΔRc (mm) is a radial distance from the origin O to the crucible inner wall on the surface of the melt. As a result, it is possible to provide the method of manufacturing a single crystal, the method enables to keep a fluctuation in a temperature gradient near the solid-liquid interface to a minimum and manufacturing the high-quality single crystal having a desired defect region formed in a crystal growth direction with high productivity and a high production yield when growing the single crystal.