Combined EPMA and AES depth profiling of a multilayer Ti-Al-O-N coating

Abstract

Abstract. In order to compare thin-film electron probe microanalysis (EPMA) and Auger electron spectroscopy (AES) regarding reliability in quantifying chemical compositions of Ti-A1-O-N coatings with depth, a multilayer was prepared on a silicon wafer by using reactive ionized cluster beam deposition technique. Within a total thickness of about 25 nm the composition of the multilayer varied step by step from Ti-A1-O-N at the bottom to A1-O at the top. AES and, as an innovation, EPMA crater edge profiling was applied to measure the composition with depth. For quantification special thin-film EPMA techniques based on Monte Carlo simulations were applied. The chemical binding states of A1 and Ti with depth were analysed using a high resolution energy analyser (MAC 3) for the AES investigations working in the direct mode. According to the deposition procedure the concentration profiles of the components varied with depth for both AES and EPMA measurements. AES provided a better depth resolution than EPMA. To get a true calibration of the depth scale an in-situ measurement method like an optical interferometry will be required. Assuming that the relative sensitivity factors are available AES depth profiling delivers concentration profiles with good accuracy. The new EPMA application provided quantitative depth profiles concerning concentration and coverage. For EPMA crater edge profiling the coating needs to be deposited on a foreign substrate because depth distributions of elements being present in both the layer and the substrate cannot be resolved.The combination of AES-depth profiling with EPMA crater edge profiling techniques is a powerful tool to analyse heterostructures quantitatively.

EPMA Sputter Depth Profiling: A New Technique for Quantitative in-Depth Analysis of Layered Structures

“…The penetration of single sublayers by the electrons is a basic prerequisite to apply the thin film quantification technique, on which the method described above is based [13]. So far the qualitative or semiquantitative results (AES) shown in Figure 3 give only tentative information about the oxide structure and the composition with depth.…”

“…The k-ratio curve in-between is subdivided into 8 sets of averaged k-ratios. The reconstruction technique is based on an EPMA thin-film quantitation method using a Monte Carlo model for the calculation of the X-ray depth distributions [13,15]. The proposed procedure is illustrated in Figure 2: the evaluation is started with the determination of the bulk composition of the substrate from the first k-ratio set by a Fig.…”

“…accurate quantitative evaluation of coverages and highly sensitive detection -with a sputtering technique as it is currently applied in Auger sputter depth profiling or crater edge linescan profiling [12]. The basic assumptions are already published by von Richthofen et al [13] and Karduck and von Richthofen [14] and are summarized in the following:…”

“…If this process is continued until the total layer is removed the total depth profile of all elements of the layer can be compiled quantitatively. Recently this was demonstrated successfully [13]. In the present paper a further step will be made by applying the Regarding the sputtering process as continuous, allows the first derivative of Equation (2) to be calculated with respect to the sputtered depth z':…”

Progress in the Characterization of Layered Structures by X-Ray Microanalysis

“…It is furthermore possible to extend this method to the analysis of unsupported layers [7]. The attainable depth resolution has been demonstrated to be, under favorable circumstances, comparable to that of Auger sputter profiling [8,9].…”