CONVERSION ELECTRON MOSSBAUER CHARACTERIZATION OF FE-TI AND FE-TIN INTERFACES IN DEPENDENCE ON PRETREATMENTS AND BIAS VOLTAGE IN PHYSICAL VAPOR-DEPOSITION

Conversion electron Mossbauer (CEMS) and Auger electron spectroscopies (AES) were used to investigate the interfaces of Ti and TiN coatings on iron. The microstructure of the interface has been studied regardin g the dependence on physical vapor deposition (PVD) parameters. In par ticular, the substrate temperature and the negative voltage (bias) app lied during the PVD process were considered. An amorphous FexTi1-x pha se has been identified at the interface of Fe/Ti. Its portion increase s with increasing bias used during the deposition process. Mossbauer s pectra also reveal a small amount of a magnetically ordered Fe-C phase in the FeTi interface. Its formation can be explained by a reaction o f the residual gas in the PVD preparation chamber with iron. However, Fe/TiN interfaces show mainly iron carbide and/or nitride phases. Iron oxides always appear in the interfaces between the substrate and the deposited Ti or TiN thin films and their contribution increases when c leaning procedures in acetone and isopropyl alcohol were applied previ ous to the PVD deposition. They occur mostly in the form of magnetical ly ordered magnetite or/and in the form of small superparamagnetic par ticles, depending on the deposition conditions. Samples of Fe/Ti and F e/TiN were annealed in vacuum at 773 K for 1 h, and CEMS spectra as we ll as AES depth profiles by argon ion sputtering were recorded. For th e Fe/Ti interface, only minor changes were found. Fe/TiN interfaces, h owever, were found to be destabilized at an elevated temperature by an oxidative decomposition of TiN combined with reactions of the interfa ce components with the substrate material.