Cover flux and method for silicon purification
First Claim
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1. A method, comprising:
- pouring molten silicon into a mold;
forming a solid layer of silicon on a top surface of the silicon, and placing flux material on the solid layer;
placing a top heater over the mold to melt the solid layer of silicon, wherein the flux material remains floating on the molten silicon;
directionally solidifying the molten silicon, from a bottom of the mold towards the top surface of the silicon; and
reacting the flux with impurities at the interface between the top surface of the silicon and the flux.
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Abstract
Cover flux devices and methods are shown. Methods and devices are shown such that, as a solidification front moves from a cooling surface of a mold towards a surface of molten silicon substantially opposite the cooling surface, impurities are driven out of the solid silicon and into the liquid to react with a flux layer on the silicon.
2 Citations
7 Claims
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1. A method, comprising:
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pouring molten silicon into a mold; forming a solid layer of silicon on a top surface of the silicon, and placing flux material on the solid layer; placing a top heater over the mold to melt the solid layer of silicon, wherein the flux material remains floating on the molten silicon; directionally solidifying the molten silicon, from a bottom of the mold towards the top surface of the silicon; and reacting the flux with impurities at the interface between the top surface of the silicon and the flux. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification