Browse Prior Art Database

Shaped Crucible

IP.com Disclosure Number: IPCOM000092487D
Original Publication Date: 1966-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Roland, PA: AUTHOR

Abstract

Crucible 8 has a 45 degrees tapered conical upper portion 10 which differentiates it from a prior crucible for aluminum evaporation described in the IBM Technical Disclosure Bulletin, Vol. 6, No. 8, January 1964, page 103. It is supported by insulating legs 20 mounted on base 22. As the power delivered by RF coil 18 to crucible 8 increases as the thickness of the wall becomes thinner, the tapered conical upper portion heats the molten aluminum 16. The latter is evaporated increasingly as it migrates to the top of crucible 8.

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Shaped Crucible

Crucible 8 has a 45 degrees tapered conical upper portion 10 which differentiates it from a prior crucible for aluminum evaporation described in the IBM Technical Disclosure Bulletin, Vol. 6, No. 8, January 1964, page 103. It is supported by insulating legs 20 mounted on base 22. As the power delivered by RF coil 18 to crucible 8 increases as the thickness of the wall becomes thinner, the tapered conical upper portion heats the molten aluminum 16. The latter is evaporated increasingly as it migrates to the top of crucible 8.

The taper at the top of crucible 8 reduces the current density of the RF field absorbed in the crucible. Thus, as the wall thickness decreases, more RF power is directly coupled to the evaporant.

Theoretically, the wall thickness of crucible 8 should be one-half the penetration depth of the applied RF field for maximum power transfer to crucible
8. The thickness of wall 12 immediately adjacent to the tapered cone is approximately equal to the penetration depth. The thickness of the lower portion is approximately equal to 2.5 times the penetration depth.

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