Polysilicon Surface Carbon Removal via High Velocity Fluid
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Solution Overview
Problem
Current methods for removing carbon contaminants from polycrystalline silicon, such as oxidative atmospheres and thermal treatments, are complex and energy-intensive, necessitating an alternative efficient means for surface carbon contamination reduction.
Innovation Solution
Subjecting polycrystalline silicon to high velocity fluid, preferably argon gas, to reduce surface carbon contamination to levels below 250 parts per billion, with optional ionization to neutralize static charge and adjust process conditions for further reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If oxidative atmospheres or thermal treatments are used to remove carbon contaminants, then carbon removal effectiveness is improved, but energy consumption and process complexity increase
Solution Approach 1:
The patent replaces thermal/chemical treatment systems with a mechanical fluid dynamic system. High velocity fluid flow (supersonic or sonic) is used to physically remove surface carbon contaminants through shear stress and impingement forces, eliminating the need for energy-intensive oxidative atmospheres or thermal treatments while achieving comparable or superior carbon removal effectiveness
Solution Approach 2:
The invention employs high velocity gas or liquid fluid streams as the primary cleaning mechanism. The pneumatic system accelerates fluid to supersonic or sonic velocities through nozzles, creating high shear stress zones that effectively strip carbon contaminants from polysilicon surfaces without requiring chemical reactions or high temperatures
2Manufacturing precision
If oxidative atmospheres or thermal treatments are used to remove carbon contaminants, then carbon removal effectiveness is improved, but process complexity increases
Solution Approach 1:
The patent replaces complex thermal processing systems with a simpler mechanical fluid dynamic system. By using high velocity fluid flow to physically remove contaminants, the invention eliminates the need for controlled oxidative atmospheres, temperature management systems, and chemical supply infrastructure, thereby reducing overall process complexity
Solution Approach 2:
The invention extracts and removes only the surface carbon contaminants through high velocity fluid impingement, leaving the bulk polysilicon material unchanged. This selective removal approach simplifies the process by focusing solely on surface cleaning without requiring complex thermal or chemical treatments that would affect the entire material structure
3Use of energy by stationary object
If high velocity fluid is used to remove surface carbon, then energy consumption is reduced, but carbon removal effectiveness may be insufficient
Solution Approach 1:
The patent employs dynamic high velocity fluid flow that can be adjusted in real-time to optimize cleaning effectiveness. By controlling fluid velocity, pressure, and flow patterns, the system adapts to different contamination levels and material types, ensuring sufficient carbon removal while maintaining energy efficiency. The dynamic nature of the fluid stream creates varying shear stress zones that enhance contaminant removal
Solution Approach 2:
The invention may employ periodic or pulsed high velocity fluid streams to remove surface carbon contaminants. By applying fluid flow in periodic bursts rather than continuous streams, the system achieves effective carbon removal while reducing overall energy consumption. The periodic action allows for optimal shear stress application during fluid contact while minimizing energy use during non-contact periods
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
Effectively reduces surface carbon contamination by at least 20% to 50% with minimal energy input, improving the quality of polycrystalline silicon for solar cells and semiconductor devices.
Implementation Method 1
subjecting the polycrystalline silicon to high velocity fluid to form a product stream comprising polycrystalline silicon, having surface carbon in an amount of less than 250 parts per billion
Implementation Method 2
subjecting the polycrystalline silicon to an impinging flow of Argon gas at a speed of at least 1 meter per second
Implementation Method 3
an ionizing source in the enclosure or integrated with the at least one stream of high velocity fluid
Data Source
AI summary
A method of removing surface carbon contamination from polycrystalline silicon comprises providing a polycrystalline silicon feed stream having surface carbon contamination, subjecting the polycrystalline silicon to a high velocity fluid selected from gas, gas/liquid mixtures, gas/solid mixtures and gas/solid/liquid mixtures to form a product stream comprising polycrystalline silicon having surface carbon in an amount of less than 200 parts per billion by weight based on weight of the polycrystalline silicon product and/or a reduction in surface carbon contamination of at least 20%. A system for conducting the method comprises an enclosure, a conveyer for moving a polycrystalline silicon feed stream through the enclosure, at least one stream of a high velocity fluid passing through outlets in the enclosure and directed at the feed stream, an ionizing source in the enclosure or integrated with the at least one stream of high velocity fluid, and an exhaust system for the enclosure.