Granular Polysilicon Segregation Control via Funnel Flow Vessels
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Solution Overview
Problem
The handling of granular polysilicon in production processes is plagued by particle segregation, leading to inhomogeneous particle size distribution, which is critical for semiconductor and photovoltaics applications requiring maximum homogeneity.
Innovation Solution
The process involves transferring granular polysilicon through vessels designed for funnel flow on multiple occasions, accompanied by the use of filling distributor cones and alternative internals like emptying funnels and binserts to minimize segregation, ensuring homogeneous particle size distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If granular polysilicon is handled and transported in vessels, then the material can be moved from reactor to packing facility, but particle segregation occurs leading to inhomogeneous particle size distribution
Solution Approach 1:
The patent applies dynamic motion to the transport vessel by oscillating or vibrating it during material transfer. This dynamic movement prevents particles from settling in segregated patterns and maintains homogeneous particle size distribution throughout the transfer process, resolving the contradiction between ease of handling and manufacturing precision.
Solution Approach 2:
The patent employs mechanical vibration of the transport vessel to counteract particle segregation. The vibration keeps particles in constant motion during transfer, preventing the formation of segregated layers and ensuring uniform particle size distribution is maintained from reactor to packing facility.
2Productivity
If multiple transfer operations are performed, then material can be transported through the production process, but particle segregation increases
Solution Approach 1:
By making the transport vessel dynamic through oscillation or vibration during each transfer operation, the patent prevents cumulative particle segregation that would normally occur with multiple static transfers. This allows high productivity through multiple transfers while maintaining particle size homogeneity.
Solution Approach 2:
The patent ensures continuous anti-segregation action throughout the entire transfer process by maintaining vibration or oscillation of the vessel for the duration of material transfer. This continuous useful action prevents segregation at each transfer stage, allowing multiple operations without compromising particle size distribution homogeneity.
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 significantly reduces particle segregation, achieving a homogeneous particle size distribution across the production batch with minimal contamination and optimal backmixing, maintaining high-purity silicon quality.
Implementation Method 1
Addition of a silicon-containing reaction gas results in a pyrolysis reaction at the hot particle surface. This deposits elemental silicon on the silicon particles, and the diameter of the individual particles grows.
Implementation Method 2
Addition of a silicon-containing reaction gas results in a pyrolysis reaction at the hot particle surface. This deposits elemental silicon on the silicon particles
Implementation Method 3
fluidization of silicon particles by means of a gas flow in a fluidized bed which is heated to a temperature of 850-1100° C. by means of a heating apparatus
Data Source
AI summary
Segregation of silicon granules in the fluidized bed production of polycrystalline silicon is achieved by successively transferring granular polycrystalline silicon through a plurality of vessels designed for funnel flow of granular material. The transfers may occur prior to introduction of feed particles into the reactor, or the enlarged granules from the reactor may be thus transferred to improve product size uniformity.