Browse Prior Art Database

Automatic Diameter Control of Crystal Growing

IP.com Disclosure Number: IPCOM000091290D
Original Publication Date: 1967-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Bochman, RA: AUTHOR [+5]

Abstract

Automatic diameter control of crystals being grown in a crystal pulling furnace is obtained by positioning a pyrometer, photocell, or other monitoring devices above the melt crucible for sensing radiation adjacent to the crystal and thus determining the crystal diameter. This method of control can be utilized with known crystal pulling furnaces, such as those in U.S. Patent 2,908,004 to Levinson or U.S. Patent 2,979,386 to Shockley.

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Automatic Diameter Control of Crystal Growing

Automatic diameter control of crystals being grown in a crystal pulling furnace is obtained by positioning a pyrometer, photocell, or other monitoring devices above the melt crucible for sensing radiation adjacent to the crystal and thus determining the crystal diameter. This method of control can be utilized with known crystal pulling furnaces, such as those in U.S. Patent 2,908,004 to Levinson or U.S. Patent 2,979,386 to Shockley.

The signal obtained from the pyrometer, e.g., of the optical type, is combined with a signal obtained from a heat sensor positioned to sense the melt temperature. The resulting differential signal is used to vary the melt temperature by controlling the crucible heater. In operation, a crystal is withdrawn at a uniform rate. An increase in the crystal diameter calls for an increase in the melt temperature. A decrease in crystal diameter calls for a decrease in the melt temperature.

The method allows close control of crystal diameter in monocrystals grown in a crystal pulling furnace.

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