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Chemisorption Technique for Trapped Gas Analysis

IP.com Disclosure Number: IPCOM000043319D
Original Publication Date: 1984-Aug-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 1 page(s) / 13K

Publishing Venue

IBM

Related People

Rubloff, GW: AUTHOR

Abstract

Trapped gas species in thin films or other materials can cause serious manufacturing problems, such as poor adhesion between layers or loss of physical integrity of the film structure. To detect the trapped gas, thermal processing or mechanical friction is used while the sample is in vacuum, in order to release the gas species. These species are normally detected by, for example, mass spectrometry. However, it is difficult to detect the released species this way, and a considerable portion of the released gas may adsorb upon the chamber walls or undergo other reactions at the chamber walls. The efficiency for collecting the released gas is also quite low in these techniques. In the present invention, the released gas is more efficiently trapped, and can be detected by chemical analysis.

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Chemisorption Technique for Trapped Gas Analysis

Trapped gas species in thin films or other materials can cause serious manufacturing problems, such as poor adhesion between layers or loss of physical integrity of the film structure. To detect the trapped gas, thermal processing or mechanical friction is used while the sample is in vacuum, in order to release the gas species. These species are normally detected by, for example, mass spectrometry. However, it is difficult to detect the released species this way, and a considerable portion of the released gas may adsorb upon the chamber walls or undergo other reactions at the chamber walls. The efficiency for collecting the released gas is also quite low in these techniques. In the present invention, the released gas is more efficiently trapped, and can be detected by chemical analysis. The trapped gas in a sample is released in vacuum using either thermal processing or mechanical friction. It is then chemisorbed (i.e., chemically bonded) to an atomically clean, reactive surface, such as that of a refractory metal. Once the released gas is bonded to the clean adsorbing surface, it is then chemically analyzed using surface analysis techniques, such as Auger electron spectroscopy or photoemission. If the adsorbing surface is held close to the source of trapped gas during the release of the gas, an appreciable fraction of the gas which is released can be captured, thereby enhancing the sensitivity of the detection technique. Enhanced sensitivity is also achieved by the use of surface analysis techniques, which are readily capable of detecting 0.001 - 0.01 atomic layers of chemisorbed species. A specific embodiment of this technique can use a pure tungsten foil located in an ultra-high vacuum chamber. The foil is mounted on a vacuum manipulator, and is resistively heated to a high temperature for a few seconds. This will liberate all contaminant species from the tungsten surface, w...