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Reduction of Contamination in a Czochralski Process

IP.com Disclosure Number: IPCOM000041498D
Original Publication Date: 1984-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Murgai, A: AUTHOR

Abstract

Contamination of the crystal grown in a Czochralski process may be reduced by providing a directed flow of inert gas and a contaminant shield to protect the crystal and melt from the contaminant sources. In the drawing, crystal 10 is pulled from the melt 11 by the conventional combined linear and rotating movement. The melt 11 is confined in the crucible 12 heated by means of an annular heater 13 surrounded by insulation 14. The crucible is supported for rotation and elevation by means of pedestal 15 and shaft 16, leading out of the furnace enclosure 17. A high purity "eliminator reservoir" 18 effectively lines the crucible 12 to provide a reservoir for the melt to prevent contamination of the melt from the crucible.

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Reduction of Contamination in a Czochralski Process

Contamination of the crystal grown in a Czochralski process may be reduced by providing a directed flow of inert gas and a contaminant shield to protect the crystal and melt from the contaminant sources. In the drawing, crystal 10 is pulled from the melt 11 by the conventional combined linear and rotating movement. The melt 11 is confined in the crucible 12 heated by means of an annular heater 13 surrounded by insulation 14. The crucible is supported for rotation and elevation by means of pedestal 15 and shaft 16, leading out of the furnace enclosure 17. A high purity "eliminator reservoir" 18 effectively lines the crucible 12 to provide a reservoir for the melt to prevent contamination of the melt from the crucible. The "eliminator reservoir" 18 is further provided with a radially extending flange 18A which overlies the heater 13 and insulation 14 and an auxiliary shield 19 to isolate other contaminant contributors. To enhance the protection, argon gas under pressure is introduced at the port 20 and induced to flow in the direction of the arrows to exit at port 21 under the influence of a reduced pressure thereat. The flow is directed by means of the double-walled gas-flow belt structure 22 which connects with the exit port 21. Since a fresh flow of argon is always present at the growth zone, the melt and crystal are protected from contamination from elements in the hot zone (heater, insulation and crucible).

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