Silicon Substrate Cooling via Inert Gas Blowing
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Solution Overview
Problem
Conventional methods for manufacturing silicon substrates from molten silicon face challenges such as high Kerf-loss during cutting, low growth speed in vertical growth techniques, and difficulties in achieving uniform solidification and blade contamination in horizontal growth techniques like Ribbon Growth on Substrate (RGS) processes.
Innovation Solution
An apparatus and method utilizing inert gas blowing during continuous casting to cool and shape silicon substrates, which includes a raw silicon feeder, melting unit, storage unit, transfer unit, and cooling unit, where inert gas is blown at a controlled rate to achieve uniform cooling and prevent contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If vertical growth technique is used to manufacture silicon substrate from molten silicon, then substrate quality is improved, but growth speed is reduced
Solution Approach 1:
The patent inverts the conventional vertical growth approach by implementing horizontal continuous casting. Instead of growing silicon vertically from a seed crystal, the molten silicon is cast horizontally onto a moving substrate, allowing rapid solidification while maintaining substrate quality. This inversion of the growth direction enables both high productivity and good substrate quality.
Solution Approach 2:
The patent replaces the mechanical blade-based shape control system with a gas flow-based control mechanism. By using inert gas blowing to control the meniscus and solidification front, the system eliminates mechanical contact while maintaining precise shape control, thereby preventing contamination and enabling faster processing.
2Productivity
If RGS process with blade is used for horizontal growth, then growth speed is improved, but blade failure and substrate contamination occur
Solution Approach 1:
The patent replaces the mechanical blade system with a pneumatic control system using inert gas blowing. The gas flow controls the meniscus position and solidification front without mechanical contact, eliminating blade failure and contamination risks while maintaining high growth speeds.
Solution Approach 2:
The patent introduces inert gas as an intermediary between the molten silicon and the substrate control mechanism. This gas mediator enables precise control of the solidification process without direct mechanical contact, preventing contamination while maintaining reliability.
3Shape
If blade is used for shape control in RGS process, then substrate shape is controlled, but mechanical contact causes contamination
Solution Approach 1:
The patent substitutes the mechanical blade contact system with a non-contact pneumatic system. Inert gas blowing controls the meniscus and solidification front to achieve precise shape control without mechanical contact, thereby eliminating contamination from blade-substrate interaction.
Solution Approach 2:
The patent uses inert gas (such as nitrogen or argon) to create an inert atmosphere during the solidification process. This inert environment prevents oxidation and contamination of the molten silicon and substrate while the gas flow controls the shape through pressure and flow rate adjustments.
4Shape
If conventional cutting processes are used to manufacture silicon substrates, then substrate shape is achieved, but Kerf-loss increases manufacturing cost
Solution Approach 1:
The patent extracts and eliminates the cutting process entirely from the manufacturing flow. By directly casting the silicon substrate in the desired shape through continuous horizontal casting, the method removes the need for subsequent cutting operations, thereby eliminating Kerf-loss and reducing material waste.
Solution Approach 2:
The patent changes the fundamental manufacturing parameter from cutting/removal to direct casting/formation. By controlling the solidification process and meniscus position through inert gas blowing, the system directly forms substrates with precise dimensions, eliminating material removal and associated losses.
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 enhances surface quality and productivity of silicon substrates by minimizing Kerf-loss, improving growth speed, and preventing blade contamination, resulting in substrates suitable for solar cells with improved efficiency.
Implementation Method 1
the cooling unit cooling the silicon melt transferred by the transfer unit. Here, the cooling unit cools the silicon melt by blowing inert gas
Implementation Method 2
a silicon melting unit disposed under the raw silicon feeder and melting the raw silicon to form molten silicon
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present disclosure provides a method and apparatus for manufacturing a silicon substrate using inert gas blowing during continuous casting to provide excellent productivity and surface quality. The apparatus includes a raw silicon feeder through which raw silicon is fed, a silicon melting unit disposed under the raw silicon feeder and melting the raw silicon to form molten silicon, a molten silicon storage unit storing the molten silicon supplied from the silicon melting unit and tapping the molten silicon to provide a silicon melt having a constant thickness, a transfer unit transferring the silicon melt tapped from the molten silicon storage unit, and a cooling unit cooling the silicon melt transferred by the transfer unit. Here, the cooling unit cools the silicon melt by blowing inert gas at a rate of 0.11~2.5 Nm3/h.