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Heat Shield to Reduce Stress during Crystal Growth

IP.com Disclosure Number: IPCOM000091292D
Original Publication Date: 1967-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Blake, LH: AUTHOR [+3]

Abstract

A baffle structure positioned above the melt in a crystal puller apparatus is provided for reducing the temperature gradient in the crystal as it is drawn from the melt. Changing the heat distribution above the surface of the melt to reduce the temperature gradient in this manner prevents formation of dislocations in the crystal.

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Heat Shield to Reduce Stress during Crystal Growth

A baffle structure positioned above the melt in a crystal puller apparatus is provided for reducing the temperature gradient in the crystal as it is drawn from the melt. Changing the heat distribution above the surface of the melt to reduce the temperature gradient in this manner prevents formation of dislocations in the crystal.

The heat shield consists of a baffle with multiple insulation layers above the surface of the melt and a single layer around the melt itself. Outside baffle 11 is disposed around the upper portion of inside baffle 12 which surrounds melt crucible 13. Baffle top 14 is usually used with the baffle assembly, particularly where higher wall temperatures are desired. The baffles are constructed of molybdenum, although other high temperature resistant materials can be used. Layers of graphite foil insulation 15 are used for more complete insulation.

In operation, the crystals are pulled from the melt at a temperature of about 1410 degrees C. The more complete insulation above the surface of the melt alters the distribution of heat to radiate more heat to the surface of the crystal above the melt. The resulting lower temperature gradient prevents formation of dislocations in the crystals so produced.

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