Browse Prior Art Database

Titanium Evaporation Source

IP.com Disclosure Number: IPCOM000042734D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Cosgrove, FJ: AUTHOR [+2]

Abstract

There are no satisfactory solutions in the art to the problem of multiple titanium evaporations from a resistance heated source filament because titanium is very reactive to the standard materials used for filaments. For example, graphite, carbon and tungsten or even boron nitride coated boats have demonstrated early failures: melts and cracks after about five titanium evaporation runs. The present solution is based on the use of an ultra-pure graphite commercially available which significantly limits the reaction between boat and charge, thus permitting the evaporation of titanium with the same filament for many runs (greater than 30 per boat).

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 95% of the total text.

Page 1 of 2

Titanium Evaporation Source

There are no satisfactory solutions in the art to the problem of multiple titanium evaporations from a resistance heated source filament because titanium is very reactive to the standard materials used for filaments. For example, graphite, carbon and tungsten or even boron nitride coated boats have demonstrated early failures: melts and cracks after about five titanium evaporation runs. The present solution is based on the use of an ultra-pure graphite commercially available which significantly limits the reaction between boat and charge, thus permitting the evaporation of titanium with the same filament for many runs (greater than 30 per boat). After various experiments have been conducted, among different ultra- pure graphites, it has been demonstrated that the graphite EK506 (manufactured by Ringsdorff, West Germany) is the most appropriate. This graphite is processed into slabs and then machined into a standard evaporation source design. The purity (<=5 ppm foreign materials) and non-wettability properties of this material cause it to be a good source filament material for titanium. The figure shows the structure of an improved ultra-pure graphite boat 10 with a large cavity 11 for containing the titanium material to be evaporated. Drilled holes 12 reduce the cross area and increase the source temperature. In addition to an increased lifetime, the above boat exhibits an excellent control during evaporation and run to run repeatabil...