Electromigration process for the purification of molten silicon during crystal growth

Patent · Fri Jan 01 00:00:00 EST 1982

OSTI ID:864209

Shlichta, Paul J ^[1]

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1. San Pedro, CA

A process for the purification of molten materials during crystal growth by electromigration of impurities to localized dirty zones. The process has particular applications for silicon crystal growth according to Czochralski techniques and edge-defined film-fed growth (EFG) conditions. In the Czochralski crystal growing process, the impurities are electromigrated away from the crystallization interface by applying a direct electrical current to the molten silicon for electromigrating the charged impurities away from the crystal growth interface. In the EFG crystal growth process, a direct electrical current is applied between the two faces which are used in forming the molten silicon into a ribbon. The impurities are thereby migrated to one side only of the crystal ribbon. The impurities may be removed or left in place. If left in place, they will not adversely affect the ribbon when used in solar collectors. The migration of the impurity to one side only of the silicon ribbon is especially suitable for use with asymmetric dies which preferentially crystallize uncharged impurities along one side or face of the ribbon.

• Research Organization: California Institute of Technology (CalTech), Pasadena, CA (United States)
• DOE Contract Number: NAS7-100
• Assignee: Lovelace, Alan M. Administrator of National Aeronautics and Space (San Pedro, CA);Shlichta, Paul J. (San Pedro, CA)
• Patent Number(s): US 4330359
• OSTI ID: 864209
• Country of Publication: United States
• Language: English

Related Subjects

electromigration
process
purification
molten
silicon
crystal
growth
materials
impurities
localized
dirty
zones
particular
applications
according
czochralski
techniques
edge-defined
film-fed
efg
conditions
growing
electromigrated
crystallization
interface
applying
direct
electrical
current
electromigrating
charged
applied
forming
ribbon
migrated
removed
left
adversely
affect
solar
collectors
migration
impurity
especially
suitable
asymmetric
dies
preferentially
crystallize
uncharged
molten materials
silicon crystal
growth process
direct electrical
solar collectors
solar collector
particular application
electrical current
crystal growth
especially suitable
molten material
adversely affect
particular applications
silicon ribbon
molten silicon
crystal growing
growth interface
growing process
asymmetric die
efg crystal
/117/136/