Non-destructive depth profile evaluation of multi-layer thin film stack using simultaneous analysis of data from multiple X-ray photoelectron spectroscopy instruments
Abstract Non-destructive depth profile evaluation of multi-layer thin film stacks using simultaneous analysis of angle-resolved x-ray photoelectron spectroscopy data from multiple instruments is demonstrated. The data analysis algorithm, called the maximum smoothness method, was originally designed to handle data from a single XPS instrument with a single x-ray energy; in this work, the algorithm is extended to provide a simultaneous analysis tool which can handle data from multiple instruments with multiple x-ray energies. The analysis provides depth profiles for multilayer stacks that cannot be obtained by conventional data analysis methods. In this paper, metal multi-layer stack samples with total thickness greater than 10 nm are analyzed with the maximum smoothness method to nondestructively obtain depth profiles, with precise information on the chemical states of atoms in the surface layer (< 2 nm) and the overall layer stack structure, which can only be obtained by analyzing the data from multiple instruments.