Browse Prior Art Database

RF Heated Crucible For Aluminum Evaporation

IP.com Disclosure Number: IPCOM000095466D
Original Publication Date: 1964-Jan-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Ames, I: AUTHOR [+2]

Abstract

An evaporation source for aluminum or other surface-migrating evaporants comprises a cylindrical crucible 1 positioned within RF coil 3. The thickness of upper wall 5 of crucible 1 is approximately equal to the skin depth, i. e., that depth at which current density induced by the RF field is reduced by a factor of 1/e times the current density at the surface. The thickness of lower wall 7 of crucible 1 is approximately equal to twice the skin depth.

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RF Heated Crucible For Aluminum Evaporation

An evaporation source for aluminum or other surface-migrating evaporants comprises a cylindrical crucible 1 positioned within RF coil 3. The thickness of upper wall 5 of crucible 1 is approximately equal to the skin depth, i. e., that depth at which current density induced by the RF field is reduced by a factor of 1/e times the current density at the surface. The thickness of lower wall 7 of crucible 1 is approximately equal to twice the skin depth.

Because of the reduced thickness of upper wall 5, power delivered per unit volume of wall material is greatest in upper portion 5. Thus, a temperature differential exists between portions 5 and 7. The temperature along portion 7 of crucible 1 is at least sufficient to volatilize evaporant material 9.

During evaporation, migration of evaporant material 9 out of crucible 1 is prevented since such material is evaporated due to the higher temperatures along the upper wall 5 and, also, by direct RF heating. Also, spattering due to slag accumulation is minimized by slight stirring of evaporant material 9 due to coupling with the RF field. Crucible 1 is supported on a ceramic mount 11.

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