Movable Rotatable Electrode Adapter for Polysilicon Rod Thermal Stress
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The Siemens method for manufacturing polysilicon rods faces challenges with increased rod diameter, leading to temperature differences between the inner and outer sides of the inverted U-shape, causing cracks and stress that can result in rod deformation, current fluctuations, and reduced crystal homogeneity, necessitating a solution for managing thermal expansion and contraction.
Innovation Solution
An apparatus with a movable and rotatable electrode adapter system that allows for horizontal movement and rotation, featuring a curved surface and spherical or flat surfaces to facilitate easy cleaning and reduce stress, preventing crack formation by accommodating thermal expansion and contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rod diameter is increased, then the productivity is improved, but the temperature difference between inner and outer sides of the bridge part increases causing crack generation
Solution Approach 1:
The electrode adapter is made movable in the horizontal direction and rotatable, allowing dynamic adjustment to accommodate thermal expansion and contraction of the polysilicon rod during deposition and cooling, preventing crack generation while enabling large diameter rods
Solution Approach 2:
The system allows positional and rotational parameter changes of the electrode adapter to compensate for thermal effects, maintaining uniform stress distribution across the rod cross-section even as diameter increases to improve productivity
2Temperature
If the current is increased to compensate heat radiation loss, then the temperature necessary for deposition is maintained, but the temperature difference between inner and outer sides increases causing stress and cracks
Solution Approach 1:
The movable and rotatable electrode adapter dynamically adjusts the electrical connection position, allowing more uniform current distribution across the rod cross-section, reducing hot spots and thermal stress while maintaining deposition temperature
Solution Approach 2:
The electrode adapter acts as an intermediary that mediates between the electrode and core wire holder, enabling flexible current distribution patterns that reduce thermal gradients and stress in large diameter rods
3Device complexity
If the electrode adapter is fixed, then the device complexity is reduced, but the cleaning efficiency decreases due to polysilicon deposition on the adapter
Solution Approach 1:
The movable electrode adapter can be repositioned and rotated to expose all surfaces to cleaning mechanisms, enabling complete removal of polysilicon deposits while maintaining a relatively simple adapter structure
Solution Approach 2:
The rotatable and movable adapter design enables self-cleaning capability where the adapter can be positioned to allow cleaning fluids or mechanisms to access all surfaces, reducing manual intervention 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
The apparatus effectively reduces crack generation during and after growth, maintaining rod integrity and crystal homogeneity, while enabling efficient cleaning and reducing contamination risks, thus improving manufacturing efficiency and quality.
Implementation Method 1
A current is supplied from the electrode 14 to the silicon core wire (not illustrated) held at a top of the core wire holder 11 via the core wire holder 11, and a surface of the silicon core wire is heated to a temperature range of about 900° C. to 1200° C. by Joule heat in a hydrogen atmosphere.
Implementation Method 2
In a process of depositing the polysilicon, the electrode, the base plate, and a bell jar are cooled by a refrigerant such as water in order to prevent the polysilicon from being deposited on the electrode and prevent metallic contamination of the polysilicon, which is caused by an increase of a temperature of the electrode, during the depositing.
Implementation Method 3
When the inverted U-shaped silicon core wire is electrically heated to a deposition temperature and a mixed gas of, for example, trichlorosilane and hydrogen as a raw material gas is brought into contact with the silicon core wire, polysilicon is vapor-grown on the silicon core wire
Data Source
AI summary
An apparatus for manufacturing polysilicon rod by a Siemens method has a base plate 20; and a holding body 100 provided on the base plate 20 so as to be movable in a horizontal direction and electrically connect between a core wire holder 1 and an electrode 4. The holding body 100 is configured to rotatably hold the core wire holder 1 with respect to the base plate 20.