Surface analysis using electron beam SNMS, applications and investigations of sputter yields

We have designed and constructed a system of optics for electron impact postionisation SNMS. The design is based on an existing parallel plate energy filter commercially operational at UMIST. The system operates with 'state of the art' efficiency in the SNMS mode of operation (a postionisation efficiency of 10^-3 to 10^-4), without significant degradation of the SIMS operation. Calibration of the SNMS mode of the system has been undertaken using standardised samples, cross-calibrated by Optical Emission Spectroscopy. These studies revealed reproducibility of < 10% in the relative sensitivity factors, and relative sensitivity factors have been assigned to several elemental species. From these studies a detection limit of < 0.01 at.% was obtained for most elemental species at Ar⁺ primary beam current of less than 10 ωA. Studies of inAsxP1-x have been used to demonstrate the linearity of SNMS for Quantitative Analysis as well as revealing the homogeneity of the analysed layers. The effects of surface roughness on the efficiency of the collection optics will also be discussed. SNMS has been applied to the investigations of the total sputter yields of some multicomponent materials. Changes in the sputter yields of copper, zinc and aluminium alloys with composition have been studied by monitoring the variations in detected sputtered neutral signal. The significance of this, particularly in the field of depth profile analysis is obvious.