Analysis of surface pre‐treatment for SAW‐substrate material (LiNbO3) and deposited thin films of Ta/Ti using ARXPS. (18th March 2014) - Vogel, U.
Abstract Next generation surface acoustic wave (SAW) devices require improved metallisations due to the demand of higher frequencies and power densities for new applications. Most likely, these metallisations will include adhesion or diffusion‐barrier layers between the piezoelectric substrate and the electrode. For improved properties, the pre‐treatment of the substrate and the chemical state of these layers is of great interest. This work gives an overview about studies of the effect of surface preparation at LiNbO3 substrates for Ta and Ti depositions and their different chemical reactions (oxidation) with the substrate surface. An ion beam and a radio‐frequency plasma source are applied for surface treatment; a dicrect current (DC)‐sputter process is used for the deposition. The characterisation of the surface's chemical changes is performed by XPS connected to a separate preparation chamber (quasi in situ) used for pre‐cleaning and film deposition. The detailed chemical layer structures at the surfaces are determined by angle‐resolved XPS and comparison with model calculations. In addition, atomic force microscope measurements are used to study the surface morphology showing almost no difference in surface roughness of the preparations. Copyright © 2014 John Wiley & Sons, Ltd.