Silicon Purification Device Preventing Impurity Re-contamination
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Solution Overview
Problem
Existing silicon purification methods, such as vacuum fusion, face challenges in achieving continuous and stable impurity removal, particularly phosphorus, due to condensed impurities dropping back into the silicon melt, leading to variations in phosphorus concentration and reduced productivity.
Innovation Solution
A silicon purification device equipped with an impurities capture device and a contamination prevention device, where the impurities reception and containment means are strategically positioned to prevent condensed impurities from dropping back into the silicon melt, ensuring stable and continuous phosphorus removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If vacuum fusion method is used to remove phosphorus from silicon melt, then phosphorus concentration is reduced, but condensed impurities drop back into the melt causing concentration variations
Solution Approach 1:
The invention extracts and removes the harmful condensed impurities from the system by providing a dedicated reception chamber that collects impurities as they condense on the cold finger, preventing them from dropping back into the silicon melt and causing concentration variations
Solution Approach 2:
The cold finger acts as an intermediary component that condenses phosphorus and other impurities from the vapor phase into liquid form, and the reception chamber serves as an intermediary space that captures these condensed impurities before they can contaminate the melt again
2Manufacturing precision
If impurities capture device is added to improve phosphorus removal, then phosphorus concentration is reduced, but device complexity increases
Solution Approach 1:
The cold finger serves multiple functions: it acts as a condensation surface for phosphorus removal, provides a collection area for condensed impurities, and prevents impurity re-contamination of the melt, thereby achieving phosphorus removal without requiring multiple separate complex components
3Ease of manufacture
If conventional vacuum fusion is used, then equipment cost is reduced, but productivity decreases due to unstable impurity removal
Solution Approach 1:
The invention performs preliminary action by providing a reception chamber that is ready to capture condensed impurities as they form, preventing the need for repeated processing cycles that would be required to correct impurity re-contamination, thereby improving productivity without increasing equipment cost
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 solution enables the stable and cost-effective production of high-purity silicon by preventing the contamination of the silicon melt with condensed impurities, maintaining low phosphorus concentrations and improving productivity.
Implementation Method 1
a processing chamber (2) whose pressure can be reduced and which is provided with a vacuum pump (1)
Implementation Method 2
heating means (5) for holding the silicon in a fused state
Implementation Method 3
the silicon raw material is heated and melted under reduced pressure
Implementation Method 4
Because the phosphorus has a higher vapour pressure than silicon, it is selectively evaporated
Implementation Method 5
the phosphorous evaporation velocity from the silicon melt
Implementation Method 6
the phosphorous is converted to an impurity condensation substance, condensed at a very high concentrations
Data Source
Figure 1~2A
Figure 2B~2C
Figure 2D~2E
AI summary
In this method for refining silicon by vacuum melting, the falling of impurity condensate from an impurity trap located above a crucible and contamination of the molten silicon are prevented. A crucible (4) for housing molten silicon (3), and a heating means (5) for heating the crucible (4) are located inside a treatment chamber (2) equipped with a vacuum pump (1); further provided are: an impurity trap having an impurity condensation unit for cooling and condensing the vapor of impurities evaporating from the liquid surface of the molten silicon; and a contamination prevention device for preventing contamination of the molten silicon, having an impurity catch unit for catching impurities when impurities trapped by the impurity trap fall.