Browse Prior Art Database

Evaporation Rate Monitor/Controller

IP.com Disclosure Number: IPCOM000074290D
Original Publication Date: 1971-Apr-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Ahn, KY: AUTHOR

Abstract

An electronic ion detector for a rate monitor in a vacuum evaporation system is shown. A filament wire is surrounded by grids 1 and 2. Two collector wires 3 and 4 are located outside grids 1 and 2. The entire unit is surrounded by anode 5.

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Evaporation Rate Monitor/Controller

An electronic ion detector for a rate monitor in a vacuum evaporation system is shown. A filament wire is surrounded by grids 1 and 2. Two collector wires 3 and 4 are located outside grids 1 and 2. The entire unit is surrounded by anode
5.

Electrons emitted by the tungsten filament are accelerated toward grid 1 or toward grid 2 by an accelerating voltage applied between these grids. This voltage is usually a sinusoidal or square wave. When grid 1 is positive with respect to the filament, electrons are accelerated toward collector 3. When the vapor beam is incident upon the inlet hole, it is ionized by these electrons and they are collected by collector 3. During the next half-cycle of grid voltage, electrons travel toward grid 2 and ionized gas is present in the vacuum chamber. These ions are collected by a collector wire 4. The collector signals from collectors 3 and 4 are processed by a phase-sensitive detector and the output signal is used to control the rate of evaporation.

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