Silicon Monocrystal Pulling Device Oxygen Concentration Polarization
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Solution Overview
Problem
Monocrystalline silicon pulled up through the Czochralski process using a horizontal magnetic field often experiences polarization in oxygen concentration, leading to inconsistent quality due to convection flow direction, which existing technologies fail to address.
Innovation Solution
A manufacturing method involving a pull-up device with a chamber, quartz crucible, and heat shield, where an asymmetric inert gas flow distribution is maintained to control convection flow direction, ensuring a constant oxygen concentration by applying a horizontal magnetic field after complete melting of the silicon material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a horizontal magnetic field is applied during the Czochralski process, then the convection flow in silicon melt is restrained, but polarization in oxygen concentration occurs in the pulled-up monocrystalline silicon
Solution Approach 1:
The patent applies a preliminary action by establishing a specific convection flow direction before applying the horizontal magnetic field. The crucible is rotated in a predetermined direction to establish the desired convection pattern, and only after this preliminary setup is complete is the horizontal magnetic field applied to restrain convection. This sequence prevents polarization by ensuring the convection flow is already in the correct state before magnetic restraint is imposed.
Solution Approach 2:
The patent employs dynamics by making the crucible rotation direction adjustable and controllable. The system dynamically adjusts the rotation direction of the crucible to establish the desired convection flow pattern. This dynamic control allows the operator to select the appropriate rotation direction (clockwise or anticlockwise) to achieve the desired convection state before magnetic field application, thereby preventing polarization.
2Stability of the object's composition
If the crucible is rotated to establish convection flow, then the convection flow direction is controlled, but the rotation process adds complexity to the pull-up device operation
Solution Approach 1:
The patent applies universality by making the crucible rotation mechanism serve multiple functions: it both melts the silicon material and establishes the desired convection flow direction. The same rotational motion that facilitates melting also creates the controlled convection patterns needed to prevent polarization. This multi-functionality reduces the need for separate mechanisms to control convection, thereby limiting the increase in device complexity.
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 method prevents polarization in the oxygen concentration of monocrystalline silicon, allowing for stable quality production by fixing the convection flow direction, thereby ensuring consistent monocrystalline silicon production without polarization.
Implementation Method 1
a horizontal magnetic field is applied to a silicon melt in the quartz crucible
Implementation Method 2
the convection flow in the silicon melt can be controlled to be clockwise or anticlockwise with respect to the direction of the horizontal magnetic field
Implementation Method 3
a silicon material in the quartz crucible is completely melted
Data Source
AI summary
A method of manufacturing monocrystalline silicon by flowing inert gas in a chamber, applying horizontal magnetic field to a silicon melt in a quartz crucible, and pulling up monocrystalline silicon includes: forming a flow distribution of a flow of the inert gas flowing between a lower end of a heat shield and a surface of the silicon melt in the quartz crucible to be plane asymmetric with respect to a plane defined by a crystal pull-up axis of the pull-up device and an application direction of the horizontal magnetic field and rotationally asymmetric with respect to the crystal pull-up axis: maintaining the formed plane asymmetric and rotationally asymmetric flow distribution in a magnetic-field-free state until a silicon material in the quartz crucible is completely melted; and applying the horizontal magnetic field to the completely melted silicon material and starting pulling up the monocrystalline silicon.