Browse Prior Art Database

Transient Trap for Retraining Water Vapor

IP.com Disclosure Number: IPCOM000089911D
Original Publication Date: 1968-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Pileur, P: AUTHOR

Abstract

This device minimizes the residual water vapor concentration in a vacuum apparatus, particularly in a cathode sputtering arrangement. After sufficiently long pumping, the vacuum established in a chamber can be about 10/-6/ Torr, but there is a concentration of water vapor condensed on the walls of the chamber. During the sputtering operation, while water vapor does not actually play a role, the molecules separate. Hydrogen molecules, due to their high mobility, contribute to the cathode temperature rise.

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Transient Trap for Retraining Water Vapor

This device minimizes the residual water vapor concentration in a vacuum apparatus, particularly in a cathode sputtering arrangement. After sufficiently long pumping, the vacuum established in a chamber can be about 10/-6/ Torr, but there is a concentration of water vapor condensed on the walls of the chamber. During the sputtering operation, while water vapor does not actually play a role, the molecules separate. Hydrogen molecules, due to their high mobility, contribute to the cathode temperature rise.

Vacuum chamber 1 includes walls 2 and bottom plate 3 to which is fastened pipe 4 connected to the vacuum pump. Cathode 6 and its associated screen 7 pass through top plate 5 via a hermetical seal. Plate 5 is also provided with a finger-shaped member 8. This can be filled with liquid nitrogen 9 or heated in order to evaporate the liquid gas. Member 8 is a transient trap for water molecules.

In operation, the pumping step is begun conventionally. When the vacuum is 10/-5/ Torr, the trap is filled with liquid nitrogen. The water vapor condenses immediately on the walls of the trap and the internal pressure reaches about 10/- 6/ Torr, since there is initially an 80% water vapor concentration.

When the condensation is completed, the trap is rapidly heated and the nitrogen evaporates. Simultaneously pumping action is continued. The condensed water is evaporated and quickly evacuated due to the high potential pumping speed now a...