The nitrogen content in tantalum nitride (TaN x ) thin films, where x indicates that TaN x is not generally stoechiometric, can be measured directly by XPS. This is the purpose of the present study. However, the XPS spectra of TaN x present electron energy loss spectroscopy (EELS) peaks that lead to a complex peak fitting, particularly for self-passivated thin films. A complete peak fitting procedure based upon Tougaard's background, the Doniach-Sunjic Function and EELS peaks, is presented. It is applied to two self-passivated TaN x thin films elaborated by reactive sputtering and presenting a different nitrogen content. The physical properties of these surfaces are interpreted in terms of Ta 4f 7/2 chemical states directly dependent on the nitrogen content. The main results are discussed and improvements are proposed to the method.

Electrical resistance of M1/M3 stack for Aluminium based technology showed anomalous values when no Ti is inserted between AlCu and cap TiN. Process investigations lead to suspect formation of AlN layer at this interface. Blanket wafers were processed at different temperatures to reproduce the layer formation and characterize the film by numerous techniques including XPS and EELS-TEM profiling. Full use of the different results shows the formation of a very thin (a few nms) and highly resistive AlN layer at the cap TiN / AlCu interface as well as a thicker but less resistive AlN layer at the bottom TiN / AlCu interface. PVD process changes were attempted to reduce the M1/M3 button stack resistance. Modification of the N2/Ar flow ratio for TiN sputtering shows slightly more stoechiometric TiN with reduced stack resistance by 35%.