Barium doping of molten silicon for use in crystal growing process
AssigneeMEMC Electronic Materials, Inc.
InventorsRichard Joseph Phillips, Steven Jack Keltner, John Davis Holder
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Abstract
A process for preparing doped molten silicon for use in a single silicon crystal growing process is disclosed. Polysilicon is doped with barium and melted in a silica crucible containing less than about 0.5% gases insoluble in silicon. During melting and throughout the crystal growing process the barium acts as a devitrification promoter and creates a layer of devitrified silica on the inside crucible surface in contact with the melt resulting in a lower level of contaminants in the melt and grown crystal.
Claims19
A process for preparing a silicon melt in a silica crucible for growing a single silicon ingot, the process comprising:
- charging polysilicon to a crucible having a bottom wall and a sidewall formation, the bottom and sidewall formation having inside and outside surfaces, and the crucible containing less than about 0.5% gases insoluble in silicon;
- melting the polysilicon to form a mass of molten silicon in the crucible;
- doping the molten mass with barium;
- and
- forming a layer of devitrified silica on the inside surface of the crucible in contact with the molten mass, the layer being nucleated by the barium in the molten mass.
A process for preparing a silicon melt in a silica crucible for growing a single silicon ingot, the process comprising:
- charging polysilicon and barium to a crucible having a bottom wall and a sidewall formation, the bottom and sidewall formation having inside and outside surfaces, and the crucible containing less than about 0.5% gases insoluble in silicon;
- melting the polysilicon to form a mass of molten silicon in the crucible;
- and
- forming a layer of devitrified silica on the inside surface of the crucible which is in contact with the molten mass, the layer being nucleated by the barium in the molten mass.
A process for preparing a silicon melt in a silica crucible for growing a single silicon ingot, the process comprising:
- charging polysilicon to a crucible having bottom wall and a sidewall formation, the bottom and sidewall formation having inside and outside surfaces, and the crucible having a tungsten doped layer on the inside bottom and sidewall formation;
- melting the polysilicon to form a mass of molten silicon in the crucible;
- doping the molten mass with barium;
- and
- forming a layer of devitrified silica on the inside surface of the crucible in contact with molten mass, the layer being nucleated by the barium in the molten mass.
Dependencies are inferred from the claim text.