Depth profiling of electrically non-conductive layered samples by RF-GDOESand HFM plasma SNMS

The work is intended to compare the capabilities of two similar depth profi ling techniques to analyse electrically nonconductive samples. In order to get a better evaluation of the depth resolution, various multilayer sandwic hes, such as SiO2/ TiO2 and Si3N4/SiO2 deposited on glass substrates have b een investigated. Optimised depth profiles are presented for both methods, glow discharge optical emission spectrometry (GDOES) and radiofrequency mod e (known as "HFM" in the SNMS literature) of plasma secondary neutral mass spectrometry (SNMS). The optimisation procedure, necessary to get the best set of plasma parameters, which result in the optimal depth resolution, is also described for one selected sample. Additionally, sputtering crater pro filometry was carried out in order to check out the flatness of the sputter ed crater. The influence of the thickness of the sample substrate on the sp uttering rate is discussed. Finally, advantages and disadvantages of the us e of these two depth profiling methods, especially for the non-conductive s amples, are concluded from this comparative study. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis of a cross-sectioned sample was carried out in order to get supplementary information. (C) 2001 Elsevier Sc ience B.V. All rights reserved.