An Analytical System for Secondary Ion Mass Spectrometry in Ultra High Vacuum

Abstract

A system for routine secondary ion mass spectrometry (sputter ion mass spectrometry) under uhv conditions has been developed. Positive as well as negative ions released from metals, semiconductors, and insulators can be measured. The system can be used for monolayer analysis (with low primary intensities) and for profile measurements in thin films. Electron induced desorption investigations are possible with the same arrangement. Means are provided to combine the secondary ion analysis with Auger spectrometry. A multitarget array allows up to 12 samples to be measured. The analytical system consists of a primary ion gun, a charge neutralizing electron source and a specially modified quadrupole mass spectrometer. Fast pulse counting technique is used for the ion detection. The uhv system is pumped by a turbomolecular pump, a liquid nitrogen cooled trap and a titanium sublimation pump. Pressures in the 10−11 Torr range can be obtained. In a number of typical examples the versatility of the instrument is demonstrated.