Polished Conveyor Liners Reduce Silicon Impurities
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Solution Overview
Problem
Polysilicon products are prone to contamination during crushing and conveyance processes, which can introduce metal and polymeric impurities, compromising their purity and electrical properties.
Innovation Solution
The use of conveyance systems and crushing tools with polished surfaces having a roughness of less than or equal to 12 microinches, made from materials like tungsten, carbon, cobalt, or their combinations, to minimize impurity transfer during the processing of silicon pieces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional crushing and conveyance tools are used, then the processing capacity is maintained, but metal and polymeric impurities contaminate the polysilicon product
Solution Approach 1:
The patent applies parameter changes by specifying precise surface roughness parameters (Ra ≤ 12 microinches, Ra ≤ 0.3 micrometers) for crushing and conveyance tool surfaces. This quantitative parameter control prevents polymeric impurity generation while maintaining processing capacity, directly resolving the contradiction between production efficiency and product purity
Solution Approach 2:
The patent employs composite material selection for crushing and conveyance tools, specifying materials such as tungsten carbide, silicon carbide, and ceramic composites. These materials combine hardness for effective crushing with low polymer generation properties and metal contamination resistance, simultaneously achieving processing capability and purity maintenance
2Manufacturing precision
If additional cleaning steps are implemented to remove impurities, then polysilicon purity is improved, but processing time and production cost increase
Solution Approach 1:
The patent implements preliminary action by pre-polishing crushing and conveyance tool surfaces to specified roughness parameters before polysilicon processing. This preventive measure eliminates polymeric impurity generation at the source, allowing the polysilicon to maintain high purity throughout processing without requiring additional cleaning steps, thus preserving productivity
Solution Approach 2:
The patent converts the potential harm of surface roughness into benefit by establishing precise roughness specifications that prevent polymer generation. By controlling the surface parameter to be sufficiently smooth, the system transforms what could be a source of contamination into a purity-preserving interface, eliminating the need for corrective cleaning operations
3Manufacturing precision
If crushing tool surfaces are polished to reduce impurity transfer, then polysilicon purity is improved, but tool manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by establishing clear, quantitative surface roughness specifications (Ra ≤ 12 microinches, Ra ≤ 0.3 micrometers) for crushing and conveyance tools. These defined parameters provide explicit manufacturing targets, simplifying the quality control process and making the polishing requirement manageable through standard surface finishing operations
Solution Approach 2:
The patent applies local quality by specifying surface roughness requirements only for the specific contact surfaces of crushing and conveyance tools that interact with polysilicon. This localized quality control focuses polishing efforts only where necessary, avoiding unnecessary complexity in non-contact areas and simplifying the overall manufacturing process
4Manufacturing precision
If polished surfaces are used to minimize contamination, then impurity transfer is reduced, but surface durability and resistance to wear may decrease
Solution Approach 1:
The patent resolves this contradiction by selecting composite materials such as tungsten carbide, silicon carbide, and ceramic composites for crushing and conveyance tools. These materials inherently combine the hardness and wear resistance needed for durable operation with surface properties that minimize polymer generation, achieving both surface durability and purity maintenance
Solution Approach 2:
The patent applies parameter changes by specifying precise surface roughness parameters (Ra ≤ 12 microinches) that balance smoothness for impurity reduction with durability considerations. These controlled parameters ensure the surface is sufficiently smooth to prevent polymer generation while maintaining structural integrity and wear resistance through proper material selection and heat treatment processes
Data Source
AI summary
A method of reducing contamination in a silicon product includes: moving silicon pieces along a conveyance system, wherein the conveyance system comprises a liner having a polished surface finish with a surface roughness of less than or equal to 12 microinches; and moving the silicon pieces across the conveyance system, wherein the silicon pieces contain a reduced number of impurities as compared to silicon pieces in contact with a liner having an unpolished surface. A crushing tool includes: crushing tool elements configured to crush silicon into fragments, wherein the crushing tool elements comprise a surface comprising a polished surface finish with a surface roughness of less than or equal to 12 microinches. A conveyance system includes: a first conveyor discharged onto a second conveyor; wherein the first conveyor comprises a first liner and wherein the second conveyor comprises a second liner.