EVALUATION OF AES DEPTH PROFILES OF THIN-FILM SYSTEMS BY APPLICATION OF NOVEL GRAPHICALLY INTERACTIVE FACTOR-ANALYSIS SOFTWARE

Factor analysis has proved to be a powerful tool for the full exploita tion of the chemical information included in the peak shapes and peak positions of spectra measured during AES depth profiling. Owing to its ability to extract the number of independent chemical components, the ir spectra and depth distributions, it is increasingly used in routine analysis. However, one has to be aware of the crucial role of the ana lyst in selecting the physically relevant result from the indefinite n umber of mathematical solutions. For this reason, he must be put in a position to define the matrix rotation and to check the resulting fact ors in a fast, flexible and transparent way. Therefore, factor analysi s software offering a graphically interactive user interface has been developed. During the necessary rotations in factor space both the dep th distributions and the corresponding spectra are displayed simultane ously, so that the analyst can judge the physical relevance of the sol ution and can quickly respond with the necessary adjustments. To demon strate the capabilities of the software in the evaluation of AES depth profile data, a TiN/Ti/SiO2 layer sequence from microelectronics tech nology was chosen. As an important result, additional layers are recog nized at the interfaces. This example demonstrates the advantages of f actor analysis and emphasizes the necessity of the analyst's knowledge on both AES spectra and the investigated material systems. In additio n, it shows the importance of a fast, direct, transparent and interact ive interface between the analyst and the mathematical tool of factor analysis.