Quantitative depth profiling in glow discharge spectroscopies ? A new deconvolution technique to separate effects of an uneven erosion crater shape

Abstract

An algorithm is presented as a concept for the quantification in direct current and radiofrequency glow discharge (GD) modes for GD optical emission spectroscopy. The algorithm is divided into excitation and sputtering part and thus it is possible to distinguish between the different excitation processes and to consider equivalent sputtering crater formations in both modes. Intensity-time profiles are affected corresponding to the method by several effects. One important effect is that sputtering occurs at a single time in different depths because of curved crater bottoms, this is usually called crater effect. The main purpose is to introduce an iterative deconvolution technique which for the quantification numerically takes into account the curved sputtering crater bottom. Input data for the deconvolution technique are the calibrated mass-time profile, the partial densities of the sample constituents and the measured final shape of the sputtering crater. Using a relatively simple model for ion sputtering the deconvolution technique improves iteratively the calculated layer structure by means of information on crater formation. The mathematical handling is illustrated for the quantification of a depth profile of a multilayer sample of ten 100 nm layers. The resulting concentration-depth profile reflects excellently the real elemental distribution of the multilayer system.

Femtosecond laser ablation elemental mass spectrometry

“…An ideal objective that ultra-short pulse ablation approaches. However, it must be tested in each single case (Präßler et al, 1996;Wetzig et al, 1997;St-Onge, 2002).…”

Radio frequency glow discharge optical emission spectroscopy: a new weapon in the depth profiling arsenal

“…In addition, methods for quantification of depth profiles (i.e., conversion from the intensity vs. time format to concentration vs. depth) are very well established and integrated into all commercial GD-OES systems [17,18]. As a final note, and analogous to high vacuum approaches, methods have also been developed to account for non-uniform sputtering across the 2-10 mm sampling area, thereby correcting the resulting time/depth profiles [19].…”

New hardware for radio frequency powered glow discharge spectroscopies and its capabilities for analytical applications

“…Therefore the possibility to apply high voltages and thus to sputter thick nonconducting materials for calibration is very essential on the way of the further development of a multi-matrix method for quantification. In this respect the new developed rf power measurement system seems to be an absolute prerequisite too [11].…”