Browse Prior Art Database

Suppression Screen for Evaporation Rate Controllers

IP.com Disclosure Number: IPCOM000096857D
Original Publication Date: 1963-Dec-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Widmer, H: AUTHOR [+3]

Abstract

Ionization gauges, not shown, generally used to measure deposition rates during evaporation/deposition processes are incapable of distinguishing between ions generated internally and charged particles emitted from an evaporation source. Accordingly, precise control of deposition rate during such processes is not possible. In drawings A and B, an electrically biased suppression screen 2 prevents both negatively and positively charged particles from reaching the ionization gauge so that precise control of deposition rate is possible, e.g., to achieve exact control of doping profiles in semiconductor materials.

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 100% of the total text.

Page 1 of 2

Suppression Screen for Evaporation Rate Controllers

Ionization gauges, not shown, generally used to measure deposition rates during evaporation/deposition processes are incapable of distinguishing between ions generated internally and charged particles emitted from an evaporation source. Accordingly, precise control of deposition rate during such processes is not possible. In drawings A and B, an electrically biased suppression screen 2 prevents both negatively and positively charged particles from reaching the ionization gauge so that precise control of deposition rate is possible, e.g., to achieve exact control of doping profiles in semiconductor materials.

For deposition by resistance heated evaporation sources as shown in A, suppression is obtained by introducing shield 1 with suppression screen 2 between crucible 3 and the ionization gauge. Screen 2 is biased negatively with respect to crucible 3.

For deposition by electron bombarded evaporation sources as shown in B, suppression is obtained by covering the opening of shield 4 with screen 2. Shield 4 surrounds filament 5 and water-cooled crucible 6 containing evaporant
7. Filament 5 is biased at a high negative (to ground) acceleration voltage. Shield 4and screen 2 are biased negatively with respect to filament 5 by passing the DC filament current through an adjustable bias resistor 9.

1

Page 2 of 2

2

[This page contains 2 pictures or other non-text objects]