Browse Prior Art Database

Evaporation Rate Monitor

IP.com Disclosure Number: IPCOM000096929D
Original Publication Date: 1962-Feb-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Giedd, GR: AUTHOR [+2]

Abstract

In the deposition of films by evaporation in a high vacuum, it is often necessary to monitor the rate of deposition. This rate monitor includes a sensing device. The latter is placed in the vacuum chamber in a position to intercept a portion of the vapor or gas stream emitted by the heated evaporant source.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 78% of the total text.

Page 1 of 2

Evaporation Rate Monitor

In the deposition of films by evaporation in a high vacuum, it is often necessary to monitor the rate of deposition. This rate monitor includes a sensing device. The latter is placed in the vacuum chamber in a position to intercept a portion of the vapor or gas stream emitted by the heated evaporant source.

The sensing device includes heated cathode 10 which emits an electron cloud. This is attracted and accelerated by helical anode coil 12. The electrons ionize some of the vapor or gas molecules in the stream being monitored. These ions are attracted to collector 14 where they are neutralized. The resulting ion current, which is measured by sensitive meter 16, is a function of the quantity of the stream passing through the monitor.

Anode 12 and collector 14 are heated by current supplied from filament transformers 18, 20, respectively. This action re-evaporates and drives off material as rapidly as it tends to deposit from the vapor or gas stream onto the anode and collector. The device monitors streams of non-conducting material without loss of sensitivity.

The sensing device includes base 22, shield 24 and, for minimization of outgassing of the structural parts, cooling coil 26. Shield 24 has vapor stream inlet and exit ports 28, 30. These are coaxial with the collector 14 and the vapor or gas stream to be monitored. Inlet port 28 is of somewhat reduced diameter so as to shield anode coil 12. The device is mounted by a socket, receivin...