Polysilicon Reactor Cooling Jacket Laminar Flow Design
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Solution Overview
Problem
The existing polysilicon manufacturing processes using chemical vapor deposition reactors face issues with turbulent gas flows, leading to increased heat loss, deviations in gas velocity, diameter, and surface temperature of silicon rods, which result in reduced productivity and quality of polysilicon due to hot spots and popcorn formation.
Innovation Solution
A polysilicon manufacturing apparatus is designed with a cooling jacket that forms a gas passage and coolant passage within the reactor, allowing the source gas to flow as a laminar flow from the lower portion to the upper portion, minimizing heat loss and deviations in gas velocity, diameter, and surface temperature by discharging gas after reaction through the cooling jacket.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If source gas is introduced from the lower portion and discharged at the upper portion to form a turbulent flow, then the chemical vapor deposition process can be maintained, but heat loss by convection increases and deviations in gas velocity, diameter, and surface temperature occur
Solution Approach 1:
The patent inverts the conventional gas flow direction by introducing source gas from the upper portion and discharging it at the lower portion. This reversal creates a laminar flow pattern that reduces convective heat loss while maintaining effective chemical vapor deposition, directly resolving the contradiction between productivity and energy loss.
Solution Approach 2:
The patent changes the flow regime parameter from turbulent flow to laminar flow by adjusting the gas introduction and discharge configuration. This parameter change reduces convective heat transfer coefficients, thereby minimizing heat loss while maintaining sufficient mass transfer for polysilicon deposition.
2Ease of operation
If turbulent flow is formed in the reactor, then gas circulation is enhanced, but hot spots are formed causing deviations in gas velocity, diameter, and surface temperature of the silicon rod
Solution Approach 1:
By inverting the gas flow direction (introduction at upper portion, discharge at lower portion), the patent transforms turbulent flow into laminar flow. This inversion eliminates hot spots and ensures uniform gas velocity distribution, thereby achieving consistent silicon rod diameter and surface temperature while maintaining adequate gas circulation for deposition.
Solution Approach 2:
The patent creates a uniformly distributed laminar flow field throughout the reactor by reversing the flow configuration. This ensures consistent thermal and mass transfer conditions at all locations around the silicon rod, eliminating local hot spots and achieving uniform deposition quality.
3Productivity
If source gas flow rate is increased to maintain deposition, then productivity is improved, but heat loss by convection increases and hot spots are formed
Solution Approach 1:
The inverted flow configuration (upper introduction, lower discharge) creates a laminar flow pattern that maintains effective deposition rates without requiring high gas velocities. This reduces convective heat loss and prevents hot spot formation, achieving both productivity and temperature uniformity.
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 laminar flow reduces heat loss by convection, decreases electric power consumption, minimizes hot spots, and enhances the uniformity of silicon rod diameters and surface temperatures, thereby improving the quality and yield of polysilicon production.
Implementation Method 1
introducing and circulating a low-temperature coolant to a coolant passage from the outside of the reactor by forming the coolant passage at the outside of the gas passage to discharge a high-temperature coolant to the outside of the reactor
Implementation Method 2
a flow of source gas is formed as a laminar flow in a chemical vapor deposition reactor
Implementation Method 3
resistor heating is generated by applying power to the Si filament
Implementation Method 4
a silicon precipitation process (alternatively, a chemical vapor deposition process) of forming polysilicon in a solid state from silane source gas
Implementation Method 5
The silicon precipitation process generates silicon particles through a hydrogen reduction reaction and pyrolysis of the silane source gas at a high temperature
Data Source
AI summary
Provided is a polysilicon manufacturing apparatus including a reactor disposed on a base plate to form a reaction chamber, a pair of electrical feedthroughs installed on the base plate to be extended to the inside of the reaction chamber, rod filaments installed on the electrical feedthroughs in the reaction chamber and connected to each other by a rod bridge at the upper end to form a silicon rod by chemical vapor deposition of source gas introduced to a gas inlet, and a cooling jacket inserted to a through-hole provided at the upper side of the reactor to be supported to the base plate, connected to a gas outlet formed on the base plate by forming a gas passage discharging the gas after reaction, and introducing and circulating a low-temperature coolant to a coolant passage from the outside of the reactor by forming the coolant passage at the outside of the gas passage to discharge a high-temperature coolant to the outside of the reactor.